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Keystone Avalanche 366LS

Fifth wheelbuilt 2025– (in production)Mixed build tierFindable on the used market
WHAT ONE COSTS
$110,900MSRP today

Still in production. A used 2023 would run roughly $65,400.

WHAT IT WEIGHS BEHIND YOUR TRUCK
~15,453 lbestimated as towed, for 2 people

dry weight 14,027 lb + fresh water (75 gal, full) 626 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 around17,170 lb (10% margin)
GVWR (the sticker maximum)16,200 lb
Tongue weight, loaded~2,605 lb (17%)
Cargo capacity2,173 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 366LS's published weights held steady. 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
Length40.8 ft
Height (incl. A/C)13.3 ft
Width8.3 ft
GVWR16,200 lb
Dry weight14,027 lb
Dry tongue weight2,365 lb
Cargo capacity2,173 lb
Sleeps6
Axles2
Fresh water75 gal
Grey water83 gal
Black water49 gal
Air conditioning15,000 BTU
Solar (standard)220 W

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

WHERE PEOPLE SLEEP
  • 1× front bedroom king bed(Permanent)—
  • 2× L-shaped sofa and dinette(Convertible)—
HOW IT'S BUILT: 4/5
WallsLaminated fiberglass
FrameAluminum
RoofWalk-on
UnderbellyEnclosed

Keystone (Mixed tier): Keystone RV

YEAR BY YEAR: WHAT CHANGED
  • 2025Introduced under the Alpine Avalanche Edition badge
FINDING ONE

Findable: a few listed nationwide most weeks. Why: Keystone is a volume manufacturer; only 2 model years; still in production. Estimated from build volume and production span, not a count of live listings.

OUR TAKE

Rear kitchen with a center living room, L-shaped sofa and a desk.

OTHER AVALANCHE FLOORPLANS
290RL · 14,000 lb · sleeps 6295RK · 15,000 lb · sleeps 2300RE · 15,000 lb · sleeps 4302RS · 15,000 lb · sleeps 4312RS · 15,000 lb · sleeps 4320RS · 15,000 lb · sleeps 4321RL · 15,000 lb · sleeps 4322RL · 15,500 lb · sleeps 4330RE · 14,300 lb · sleeps 4332MK · 15,000 lb · sleeps 4338GK · 15,500 lb · sleeps 4346FL · 16,500 lb · sleeps 6352BH · 15,500 lb · sleeps 8360FL · 16,500 lb · sleeps 6the whole line →
Find one for sale

Live listings for the 366LS 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 Avalanche line ↗

Is the 366LS 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.