Grand Design Momentum 399M
Fifth wheelbuilt 2026– (in production)Mixed build tierPatient search on the used market
WHAT ONE COSTS
$190,300MSRP today
Still in production. A used 2023 would run roughly $112,300.
WHAT IT WEIGHS BEHIND YOUR TRUCK
~21,138 lbestimated as towed, for 2 people
dry weight 19,170 lb + fresh water (140 gal, full) 1,168 lb + propane + battery 200 lb + gear for 2 600 lb. Brochure dry weight omits water, propane, batteries and your gear; this estimate doesn't.
You want a tow rating around23,490 lb (10% margin)
GVWR (the sticker maximum)23,500 lb
Tongue weight, loaded~3,756 lb (18%)
WHICH TOW VEHICLES IT FITS: 8 OF 95
Judged the way the app judges: estimated loaded weight against each vehicle's rating less a 10% margin, per model year, because the 399M's published weights held steady. Fifth wheels also need a pickup bed and are held to the fifth-wheel rating where published.
| VEHICLE | TOW RATING | VERDICT |
|---|---|---|
| Chevrolet Silverado / GMC Sierra 3500HD (Duramax DRW, gooseneck) '20-26 | 36,000 lb | fits, loaded, with 10% margin |
| Ford F-350 Super Duty (6.7 diesel DRW, gooseneck) '17-19 | 32,500 lb | fits, loaded, with 10% margin |
| Ford F-350 Super Duty (6.7 diesel DRW, gooseneck) '20-22 | 37,000 lb | fits, loaded, with 10% margin |
| Ford F-350 Super Duty (6.7 HO diesel DRW, gooseneck) '23-26 | 38,000 lb | fits, loaded, with 10% margin |
| Ford F-450 Super Duty (6.7 HO diesel DRW, gooseneck) '23-26 | 40,000 lb | fits, loaded, with 10% margin |
| Ram 3500 (6.7 Cummins DRW, gooseneck) '13-18 | 31,210 lb | fits, loaded, with 10% margin |
| Ram 3500 (6.7 Cummins HO DRW, gooseneck) '25-26 | 36,610 lb | fits, loaded, with 10% margin |
| Ram 3500 (6.7 Cummins HO DRW, gooseneck) '19-24 | 37,090 lb | fits, loaded, with 10% margin |
The 87it doesn't fit
- Chevrolet Colorado / GMC Canyon (2.7 Turbo HO, tow pkg) '23-26: over by ~14,208 lb loaded
- Chevrolet Colorado / GMC Canyon (2.8 Duramax) '15-22: over by ~14,208 lb loaded
- Chevrolet Silverado / GMC Sierra 1500 (6.2 V8, max tow) '19-26: over by ~11,868 lb loaded
- Chevrolet Silverado / GMC Sierra 2500HD (Duramax, max tow) '24-26: over by ~953 lb loaded
- Chevrolet Silverado / GMC Sierra 2500HD (Duramax) '20-23: over by ~4,478 lb loaded
- Chevrolet Silverado / GMC Sierra 2500HD (Duramax) '11-19: over by ~4,848 lb loaded
- Chevrolet Silverado / GMC Sierra 3500HD (Duramax DRW, gooseneck) '11-19: over by ~168 lb loaded
- Chevrolet Silverado 1500 (max tow) '14-18: over by ~10,698 lb loaded
- Chevrolet Silverado EV (4WT) '24-26: over by ~9,888 lb loaded
- Chevrolet Suburban (5.3 V8, max tow) '21-26: no pickup bed (cannot hitch a fifth wheel)
- Chevrolet Tahoe (5.3 V8, max tow) '21-26: no pickup bed (cannot hitch a fifth wheel)
- Chevrolet Traverse (tow pkg) '18-26: no pickup bed (cannot hitch a fifth wheel)
- Chrysler Pacifica '17-26: no pickup bed (cannot hitch a fifth wheel)
- Dodge Durango (5.7 / 6.4 Hemi, tow pkg) '14-26: no pickup bed (cannot hitch a fifth wheel)
- Ford Bronco 4-dr (2.7 EcoBoost, tow pkg) '21-26: no pickup bed (cannot hitch a fifth wheel)
- Ford Expedition (3.5 EcoBoost, tow pkg) '25-26: no pickup bed (cannot hitch a fifth wheel)
- Ford Expedition (3.5 EcoBoost, tow pkg) '18-24: no pickup bed (cannot hitch a fifth wheel)
- Ford Explorer (3.0 EcoBoost, tow pkg) '20-26: no pickup bed (cannot hitch a fifth wheel)
- Ford F-150 (3.5 EcoBoost, max tow) '24-26: over by ~11,418 lb loaded
- Ford F-150 (3.5 EcoBoost, max tow) '15-20: over by ~10,428 lb loaded
- Ford F-150 (3.5 EcoBoost, max tow) '21-23: over by ~8,538 lb loaded
- Ford F-150 (3.5 EcoBoost, max tow) '11-14: over by ~10,968 lb loaded
- Ford F-150 Lightning (max trailer tow) '22-26: over by ~12,138 lb loaded
- Ford F-250 Super Duty (6.7 diesel, gooseneck) '20-22: over by ~618 lb loaded
- Ford F-250 Super Duty (6.7 diesel, tow pkg) '17-19: over by ~4,938 lb loaded
- Ford F-250 Super Duty (6.7 diesel) '11-16: over by ~6,198 lb loaded
- Ford F-250 Super Duty (6.7 HO diesel, gooseneck) '23-26: over by ~438 lb loaded
- Ford F-350 Super Duty (6.7 diesel DRW, gooseneck) '11-16: over by ~1,698 lb loaded
- Ford Maverick (2.0 EcoBoost, 4K tow pkg) '22-26: over by ~17,538 lb loaded
- Ford Ranger (2.3 EcoBoost, tow pkg) '19-23: over by ~14,388 lb loaded
- Ford Ranger (2.7 EcoBoost, tow pkg) '24-26: over by ~14,388 lb loaded
- Ford Transit (HD tow pkg) '15-26: no pickup bed (cannot hitch a fifth wheel)
- GMC Acadia (tow pkg) '20-26: no pickup bed (cannot hitch a fifth wheel)
- GMC Hummer EV Pickup '22-26: over by ~14,388 lb loaded
- GMC Sierra EV '24-26: over by ~10,338 lb loaded
- GMC Yukon / Yukon XL (5.3 V8, max tow) '21-26: no pickup bed (cannot hitch a fifth wheel)
- Honda Odyssey '18-26: no pickup bed (cannot hitch a fifth wheel)
- Honda Passport (AWD) '19-26: no pickup bed (cannot hitch a fifth wheel)
- Honda Pilot (AWD, tow pkg) '16-26: no pickup bed (cannot hitch a fifth wheel)
- Honda Ridgeline (AWD) '17-26: over by ~16,638 lb loaded
- Hyundai Palisade (tow pkg) '20-26: no pickup bed (cannot hitch a fifth wheel)
- Hyundai Santa Cruz (2.5T AWD) '22-26: over by ~16,638 lb loaded
- Jeep Gladiator (3.6 V6, max tow) '20-26: over by ~14,208 lb loaded
- Jeep Grand Cherokee (5.7 Hemi) '11-21: no pickup bed (cannot hitch a fifth wheel)
- Jeep Grand Cherokee (WL, tow pkg) '22-26: no pickup bed (cannot hitch a fifth wheel)
- Jeep Grand Cherokee L (5.7 Hemi) '21-26: no pickup bed (cannot hitch a fifth wheel)
- Jeep Grand Wagoneer (Hurricane, max tow) '22-26: no pickup bed (cannot hitch a fifth wheel)
- Jeep Wagoneer (Hurricane, max tow) '22-26: no pickup bed (cannot hitch a fifth wheel)
- Jeep Wrangler Unlimited 4-dr (tow pkg) '18-26: no pickup bed (cannot hitch a fifth wheel)
- Kia Telluride (tow pkg) '20-26: no pickup bed (cannot hitch a fifth wheel)
- Land Rover Defender '20-26: no pickup bed (cannot hitch a fifth wheel)
- Land Rover Discovery '17-26: no pickup bed (cannot hitch a fifth wheel)
- Lexus GX 550 (tow pkg) '24-26: no pickup bed (cannot hitch a fifth wheel)
- Lexus LX 600 '22-26: no pickup bed (cannot hitch a fifth wheel)
- Mazda CX-90 (3.3 turbo, tow pkg) '24-26: no pickup bed (cannot hitch a fifth wheel)
- Mercedes-Benz Sprinter '19-26: no pickup bed (cannot hitch a fifth wheel)
- Nissan Armada (3.5 twin-turbo, tow pkg) '25-26: no pickup bed (cannot hitch a fifth wheel)
- Nissan Armada (tow pkg) '17-24: no pickup bed (cannot hitch a fifth wheel)
- Nissan Frontier (3.8 V6, tow pkg) '22-26: over by ~14,703 lb loaded
- Nissan Pathfinder (tow pkg) '22-26: no pickup bed (cannot hitch a fifth wheel)
- Nissan Titan (5.6 V8, tow pkg) '17-24: over by ~12,353 lb loaded
- Nissan Titan XD (Cummins diesel) '16-19: over by ~9,698 lb loaded
- Ram 1500 (3.0 Hurricane, max tow) '25-26: over by ~10,688 lb loaded
- Ram 1500 (5.7 Hemi eTorque, max tow) '19-24: over by ~9,663 lb loaded
- Ram 1500 (5.7 Hemi, max tow) '11-18: over by ~11,578 lb loaded
- Ram 2500 (6.7 Cummins HO) '19-26: over by ~3,138 lb loaded
- Ram 2500 (6.7 Cummins) '11-18: over by ~4,958 lb loaded
- Ram ProMaster '14-26: no pickup bed (cannot hitch a fifth wheel)
- Rivian R1S '22-26: no pickup bed (cannot hitch a fifth wheel)
- Rivian R1T '22-26: over by ~11,238 lb loaded
- Subaru Ascent '19-26: no pickup bed (cannot hitch a fifth wheel)
- Subaru Outback (XT / Wilderness) '20-26: no pickup bed (cannot hitch a fifth wheel)
- Tesla Cybertruck '24-26: over by ~11,238 lb loaded
- Tesla Model X (tow pkg) '16-26: no pickup bed (cannot hitch a fifth wheel)
- Tesla Model Y (tow pkg) '21-26: no pickup bed (cannot hitch a fifth wheel)
- Toyota 4Runner (4.0 V6) '11-24: no pickup bed (cannot hitch a fifth wheel)
- Toyota 4Runner (i-Force Max) '25-26: no pickup bed (cannot hitch a fifth wheel)
- Toyota Grand Highlander (i-Force Max) '24-26: no pickup bed (cannot hitch a fifth wheel)
- Toyota Highlander (tow pkg) '20-26: no pickup bed (cannot hitch a fifth wheel)
- Toyota Land Cruiser (i-Force Max) '24-26: no pickup bed (cannot hitch a fifth wheel)
- Toyota Sequoia (i-Force Max, tow pkg) '23-26: no pickup bed (cannot hitch a fifth wheel)
- Toyota Sienna '21-26: no pickup bed (cannot hitch a fifth wheel)
- Toyota Tacoma (i-Force Max, tow pkg) '24-26: over by ~15,288 lb loaded
- Toyota Tacoma (V6, tow pkg) '16-23: over by ~15,018 lb loaded
- Toyota Tundra (5.7 V8, tow pkg) '11-21: over by ~11,958 lb loaded
- Toyota Tundra (i-Force Max, tow pkg) '22-26: over by ~10,338 lb loaded
- Volkswagen Atlas (tow pkg) '18-26: no pickup bed (cannot hitch a fifth wheel)
These verdicts assume 2 people aboard with typical gear. See the margin for your truck and your crew →
THE SPECS
Length44.8 ft
Height (incl. A/C)13.5 ft
Width8.4 ft
Interior height8.4 ft
GVWR23,500 lb
Dry weight19,170 lb
Dry tongue weight3,406 lb
Sleeps5
Slide-outs3
Axles3
Fresh water140 gal
Grey water104 gal
Black water52 gal
Solar (standard)330 W
A missing row means the maker never published that figure: unknown, not zero.
WHERE PEOPLE SLEEP
- 1× Front queen bed, king optional(Permanent)60×80
- 1× Garage loft/Happijac bed(Stow-away)—
- 1× Garage sofa converts to a bed(Convertible)—
HOW IT'S BUILT: 4/5
WallsLaminated fiberglass
FrameAluminum
RoofWalk-on
UnderbellyEnclosed
Grand Design (Mixed tier): Grand Design's toy hauler family, spanning four sub-series: the flagship M-Class fifth wheels (the plain M/MS/TH codes), the lighter G-Class fifth wheels (3xxG), G-Class travel trailers (2xG/3xG), and the entry MAV travel trailers. The premium fifth wheels are laminated aluminum-cage coaches on par with Solitude; MAV is a lighter traditional build, which is why the line as a whole reads mixed rather than uniformly better.
YEAR BY YEAR: WHAT CHANGED
- 2026Introduced
FINDING ONE
Patient search: weeks of watching, and probably some travel. Why: only one model year; still in production. Estimated from build volume and production span, not a count of live listings.
OUR TAKE
Heaviest and priciest Momentum at 19,170 lb dry — 12 ft 6 in. garage.
OTHER MOMENTUM FLOORPLANS
17MAV · 9,950 lb · sleeps 221G · 11,000 lb · sleeps 622MAV · 9,950 lb · sleeps 523G · 13,000 lb · sleeps 624MAV · 11,000 lb · sleeps 325G · 13,000 lb · sleeps 627G · 13,000 lb · sleeps 627MAV · 11,000 lb · sleeps 628G · 13,000 lb · sleeps 628MAV · 11,000 lb · sleeps 629GS · 13,000 lb · sleeps 630G · 13,000 lb · sleeps 731G · 13,000 lb · sleeps 6320G · 16,400 lb · sleeps 6the whole line →
Find one for sale
Live listings for the 399M on the big marketplaces. Each search opens pre-filled with this exact floorplan:
Inventory varies by site and day. Slim pickings? search the whole Momentum line ↗
Is the 399M your #1, or just a spec sheet?
These are the facts. Whether it beats the other six thousand rigs for you depends on what you care about. Set your priorities as sliders, switch on your hard limits, and watch the whole market re-rank around them. Every exclusion explained, every margin shown.
See where it ranks for you →Data compiled from manufacturer spec sheets, retrieved 2026-07.