The Fabco 688-0578 (also cataloged as 6880578) is a genuine OEM hex jam nut specified to a 1-1/2-12 UNF-2B thread form and manufactured to Grade 5 strength. The UNF-2B designation indicates a unified fine thread, 2B fit class, suited to the close tolerances common in transfer case, steerable drive axle, and related heavy-duty drivetrain assemblies where Fabco hardware is called out. Using the exact OEM-spec nut matters in these applications: thread pitch, fit class, and grade all affect clamping load and fastener integrity. Pro Gear and Transmission stocks genuine Fabco parts; call us to confirm this is the correct part number for your specific assembly.
Features
Genuine OEM Fabco part, number 688-0578 or 6880578
1-1/2-12 UNF-2B thread specification: unified fine thread, 2B fit class
Grade 5 strength rating
Hex jam nut profile
Designed for Fabco transfer case and steerable drive axle assemblies
Sold by Pro Gear and Transmission
Tech Specs
- Thread: 1-1/2-12 UNF-2B (Unified Fine Thread, 2B fit class)
- Grade: Grade 5
- Style: Hex Jam Nut
- Part Number: 688-0578 or 6880578
- Brand: Fabco (Genuine OEM)
