The GM TH350 adapter to the Dana 18 / 20 is a short 1.850 inch and the overall length of transmission and adapter is 23.35 inch. The adapter material is 356 T-6 heat treated aluminum alloy and the adapter has a provision for a transmission. The adapter kit includes a adapter housing, 6 spline spud shaft, bearing, snap ring, O-ring, seal, gasket, fastening hardware and adapter instruction. This adapter assembly will fit any Dana Spicer 18 / 20, Scout version with a 6 tooth female drive gear. The transfer case index to the new adapter will require an index retainer & sealed bearing. Please I.D. the transfer case bore size (3-1/8 inch) small hole or (4 inch) large hole for proper retainer. Additional information can be obtained in our on-line catalog, Jeep & Scout Vehicle Section: Transfer Case Information, Jeeps 1941-79.This adapter kit is designed for exclusive use with the 4wd GM TH350 automatic transmission. This GM automatic was commonly found stock in vehicles from 1969-81. The Turbo Hydramatic 350 three speeds automatic is one of the most transmissions available in GM 4x4 trucks. The stock 4wd output shaft protrudes from the back of the case approx 1 inch. 1980-81 model TH350 4wd output protrudes out 2.750 inch. And this TH350 also uses a lock-up torque convert, and was always used with an aluminum transfer case.
Advance Adapters got its start in Downey, California in 1971 with a single adapter mating a Muncie car 4-speed to a Jeep Dana 18 transfer case. Eventually headers, overdrives, motor mounts and linkage brackets were added to the offerings to complement their core adapter components. When interest in rock crawling spiked in the mid-1990s, Advance Adapters offered low ratio transmission swaps then switched gears into the ultra-low gear transfer case arena. Today, the company is based in Paso Robles, California and their engine and transmission conversions for Jeeps are in kit form and sold as individual components. Shop Advance Adapters Now