21K Underbox Double Pivot Fifth Wheel Hitch For Reese UMS Brackets #8550033

Tow your fifth wheel with confidence using the Demco Hijacker SL Series 21K Underbox Double Pivot Fifth Wheel Hitch (Part #8550033). Engineered for long-box trucks with the Reese UMS bracket system, this fixed-mount fifth wheel hitch combines a sturdy 21,000 lb capacity with thoughtful design touches that deliver a smoother, safer ride — backed by Demco's reputation for quality and built right here in the USA. (Have a short-bed truck instead? See the Autoslide options: 21K above-bed (8550035), 21K above-bed WITH rails (8550036), 21K UMS Under-Bed (8550037), 21K Ford Prep Package (8550038), 18K above-bed (8550034), or 18K UMS Under-Bed (8550022).)

• 21,000 lb gross trailer weight rating
• 5,250 lb gross pin weight rating

That puts it in the right capacity range for most heavy fifth wheel applications — from large travel-style fifth wheels to toy haulers and full-size rigs.

Underbox (UMS) Mounting — A Cleaner Truck Bed

The standout feature of this hitch is its unique under-bed mounting system (UMS) — it uses the Reese UMS brackets installed under your truck bed rather than rails sitting on top. The result: when the hitch is removed, your truck box is completely free of bed rails, leaving you with full bed usability for hauling other loads. No more working around rails when your bed isn't being used for towing.

Wrap-Around Jaw + Double Pivot Head = Smoother Ride

Two design features set this hitch apart in terms of ride quality:

• Wrap-around jaw with locking bar for a smoother, safer, more secure connection to your kingpin
• Double-pivot head with polyurethane bumpers eliminates side-to-side movement when uncoupled and cushions the pivot action when coupled — meaning less jarring through the truck cab when towing

Adjustable Vertical Height

The hitch offers 16" to 19" of vertical height adjustment, giving you the range to dial in a level connection between your truck and fifth wheel regardless of how the two sit together. A 4-way pivot accommodates the natural movement of towing over uneven terrain.

Long-Box Application

The 8550033 is built specifically for long-box truck applications. If your truck has a short box, you'll want a slider hitch instead to avoid kingpin-to-cab collisions during tight turns.

Quick, Clean Installation

Installation is straightforward — no drilling, no cutting required. Bed hole plugs are included for a clean appearance when the hitch is removed. Estimated install time is approximately 2 hours. (Please note: mounting hardware is not included — confirm you have or need the appropriate Reese UMS brackets for your truck before ordering.)

Built to Last

The hitch features a black powder-coated finish for long-lasting corrosion resistance and a clean look. Made in the USA and backed by a limited 5-year warranty.

Key Features

• 21,000 lb gross trailer weight / 5,250 lb pin weight rating
• Under-bed (UMS) mounting — leaves truck box free of rails when hitch is removed
• Wrap-around jaw with locking bar for smoother, safer kingpin connection
• Double-pivot head with polyurethane bumpers for cushioned coupling
• 4-way pivot
• 16"–19" vertical height adjustment
• Long-box application
• No drilling or cutting required
• Bed hole plugs included
• Black powder-coated finish
• Made in USA
• ~2-hour estimated install
• Backed by a limited 5-year warranty

Specifications

• Brand: Demco
• Series: Hijacker SL
• Part Number: 8550033
• Type: Underbox Double-Pivot Fifth Wheel Hitch
• Capacity: 21,000 lb GTW / 5,250 lb pin weight
• Mount Type: Fixed
• Vertical Height Adjustment: 16"–19"
• Pivot Type: 4-way (double pivot head)
• Material: Steel
• Finish: Black powder coated
• Mounting Hardware Included: No (uses Reese UMS brackets)
• Drilling Required: No
• Cutting Required: No
• Lock Position: Handle
• Application: Long-box trucks
• Estimated Install Time: ~2 hours
• Country of Origin: USA
• Warranty: Limited 5-year