What You're Actually Buying
This is the right-hand wing/skid casting for the JOST JSK37C fifth wheel top plate — not the whole fifth wheel, just the RH casting that bolts into the assembly and takes the wear from the kingpin locking mechanism riding across it.
JOST used this casting across a range of fifth wheel builds through the JSK37 lineup, so it shows up under a handful of different assembly numbers depending on when the trailer was built and what dealer stocked it.
Because it's a casting, not a full unit, you need to know it's handed — right vs left matters here, and bolting the wrong side on will throw your kingpin engagement off.
Why These Numbers Cross
JOST's own part numbering isn't consistent year to year — SK7322150Z, SK2121, and JSK37CW all reference the same casting family as JSK 37C, just tagged differently by service kit, catalog year, or whether it was sold as a standalone casting versus part of a repair kit.
The casting geometry, bolt pattern, and wing thickness are what actually matter for fit — not the number stamped on the box. Two numbers can cross clean if the casting dimensions match, even if JOST changed the part number when they updated a parts catalog or bundled it differently.
Don't just match numbers off a label. Pull your old casting, check for the JOST stamp, and measure the wing thickness and bolt spacing before you order. If the old part's numbers are worn off, get us your fifth wheel's base model and we'll work it from there.
Ordering From PartStop
We stock this in Tacoma and it's typically same-day if you're local — walk in, we'll match it to your old casting on the counter before you leave.
Ship nationwide if you're not near us, usually next-day or two-day depending on where your yard sits.
Comes with our standard 6+ month warranty. This is a heavy application part running under load constantly, so if it's not right, don't force it on — call us and we'll sort it before it's a bigger problem on the road.
JSK 37C Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to JSK 37C. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| JOST | JSK37C-Z150, SK7322150Z, SK2121, JSK37CW |
Frequently asked questions
Does JSK 37C fit my trailer's fifth wheel?
Depends on what JOST fifth wheel base you've got under there. JSK 37C is a right-hand casting for the JSK37 series — give us the VIN or better yet the numbers off your old casting and we'll confirm before you order, not after.
Is JSK 37C the same as SK7322150Z?
They cross-reference to the same casting family, yes, but 'same' depends on your specific build year and whether JOST changed the casting spec when they issued that number. Pull the old part and check the stamp against what we've got before assuming it's a straight swap.
What should I check before I order this?
Confirm it's right-hand, not left — bolting the wrong side on will mess up kingpin engagement. Also check wing thickness and bolt spacing against your old casting. If numbers are worn off the old part, snap a photo and call us.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
Need the part, not just the reading?
Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.