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Keystone Montana 3931FB

Fifth wheelbuilt 2021–23Mixed build tierFindable on the used market
WHAT ONE COSTS
$82,300est. used (2023, 3 yr old)

Sticker was $132,923 in 2023. Out of production since 2023, so the used market is the only way to buy one. Estimate assumes a 2023 unit.

WHAT IT WEIGHS BEHIND YOUR TRUCK
~15,134 lbestimated as towed, for 2 people

dry weight 13,750 lb + fresh water (70 gal, full) 584 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 around16,820 lb (10% margin)
GVWR (the sticker maximum)16,500 lb
Tongue weight, loaded~2,785 lb (18%)
Cargo capacity2,750 lb
WHICH TOW VEHICLES IT FITS: 18 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 3931FB's published weights changed mid-run. Fifth wheels also need a pickup bed and are held to the fifth-wheel rating where published.

VEHICLETOW RATINGVERDICT
Chevrolet Silverado / GMC Sierra 2500HD (Duramax, max tow) '24-2622,500 lbfits, loaded, with 10% margin
Chevrolet Silverado / GMC Sierra 2500HD (Duramax) '20-2318,510 lbfits, loaded, with 10% margin
Chevrolet Silverado / GMC Sierra 2500HD (Duramax) '11-1918,100 lbfits, loaded, with 10% margin
Chevrolet Silverado / GMC Sierra 3500HD (Duramax DRW, gooseneck) '20-2636,000 lbfits, loaded, with 10% margin
Chevrolet Silverado / GMC Sierra 3500HD (Duramax DRW, gooseneck) '11-1923,300 lbfits, loaded, with 10% margin
Ford F-250 Super Duty (6.7 diesel, gooseneck) '20-2222,800 lbfits, loaded, with 10% margin
Ford F-250 Super Duty (6.7 diesel, tow pkg) '17-1918,000 lbfits, loaded, with 10% margin
Ford F-250 Super Duty (6.7 HO diesel, gooseneck) '23-2623,000 lbfits, loaded, with 10% margin
Ford F-350 Super Duty (6.7 diesel DRW, gooseneck) '17-1932,500 lbfits, loaded, with 10% margin
Ford F-350 Super Duty (6.7 diesel DRW, gooseneck) '20-2237,000 lbfits, loaded, with 10% margin
Ford F-350 Super Duty (6.7 diesel DRW, gooseneck) '11-1621,600 lbfits, loaded, with 10% margin
Ford F-350 Super Duty (6.7 HO diesel DRW, gooseneck) '23-2638,000 lbfits, loaded, with 10% margin
Ford F-450 Super Duty (6.7 HO diesel DRW, gooseneck) '23-2640,000 lbfits, loaded, with 10% margin
Ram 2500 (6.7 Cummins HO) '19-2620,000 lbfits, loaded, with 10% margin
Ram 2500 (6.7 Cummins) '11-1817,980 lbfits, loaded, with 10% margin
Ram 3500 (6.7 Cummins DRW, gooseneck) '13-1831,210 lbfits, loaded, with 10% margin
Ram 3500 (6.7 Cummins HO DRW, gooseneck) '25-2636,610 lbfits, loaded, with 10% margin
Ram 3500 (6.7 Cummins HO DRW, gooseneck) '19-2437,090 lbfits, loaded, with 10% margin
The 77it doesn't fit

These verdicts assume 2 people aboard with typical gear. See the margin for your truck and your crew →

THE SPECS
Length41.3 ft
Height (incl. A/C)13.4 ft
GVWR16,500 lb
Dry weight13,750 lb
Dry tongue weight2,530 lb
Cargo capacity2,750 lb
Sleeps4
Fresh water70 gal
Grey water88 gal
Black water88 gal

A missing row means the maker never published that figure: unknown, not zero.

WHERE PEOPLE SLEEP
  • 1× front bedroom king (60×80 queen available)(Permanent)60×80
  • 1× hide-a-bed sofa(Convertible)—
HOW IT'S BUILT: 4/5
WallsLaminated fiberglass
FrameAluminum
RoofWalk-on
UnderbellyEnclosed

Keystone (Mixed tier): Keystone's flagship — the best construction in the Keystone stable (laminated walls, aluminum frame, long structural warranty), but Thor-era QC inconsistency keeps the line at mixed.

YEAR BY YEAR: WHAT CHANGED
YEARSGVWRDRYMSRP
202116,500 lb13,613 lb$100,403
2022–2316,500 lb13,750 lb$132,923
  • 2021Introduced alongside the 3930FB
  • 2023Dropped for 2024
FINDING ONE

Findable: a few listed nationwide most weeks. Why: Keystone is a volume manufacturer. Estimated from build volume and production span, not a count of live listings.

OUR TAKE

Front-bath suite plan; successor to the 2021-only 3930FB.

OTHER MONTANA FLOORPLANS
3100RL · 19,000 lb · sleeps 43120RL · 16,000 lb · sleeps 43121RL · 16,350 lb · sleeps 43123RL · 16,350 lb · sleeps 43230CK · 16,680 lb · sleeps 43231CK · 16,680 lb · sleeps 43531RE · 16,480 lb · sleeps 43532SP · 16,500 lb · sleeps 43700LK · 16,400 lb · sleeps 63740FK · 16,500 lb · sleeps 63760FL · 16,800 lb · sleeps 63761FL · 18,000 lb · sleeps 63762BP · 16,980 lb · sleeps 63763BP · 16,980 lb · sleeps 6the whole line →
Find one for sale

Live listings for the 3931FB on the big marketplaces. Each search opens pre-filled with this exact floorplan:

RV Trader ↗Camping World ↗FB Marketplace ↗Google ↗

Inventory varies by site and day. Slim pickings? search the whole Montana line ↗

Is the 3931FB 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 dealer and aggregator listings, retrieved 2026-07.