Advance Adapter
Our GM SM420 adapter to the Dana 18 / 20 is 4.00” in length. The adapter material is 356 T-6 heat treated aluminum alloy, and the adapter has a provision for a transmission mount. Our kit will include a adapter housing, spud shaft with 6 spline for drive gear, mount block, set collar, gaskets, seal, nylon lock nut, fastening hardware and adapter instructions.
Transfer case
Stock 6 spline transfer case: 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") small hole or (4") 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.
Stock 10 spline transfer case: This adapter assembly will also fit any Dana Spicer 18 / 20 version with a 10 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") small hole or (4") 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.
You will need to purchase a new 6 spline drive gear, J0809297. This *20 Degree pressure angle gear fits model 18 transfer cases with 2.46:1, w/ T14 transmission, 1 ¼” intermediate shaft CJ with Buck V6 (68-71).
If you have a Jeepster, you will need J5354506. This is a 17 Degree pressure angle gear: Model 18 transfer cases with 2.03:1, w/ T14 transmission, 1 ¼” intermediate shaft Jeepster/CJ (67-74).
Transmission
The kit is designed for exclusive use with the GM SM420 4 speed transmission. The SM420 was used in GM trucks 1947 to 1968 and has a 10 spline output shaft and was used in both 2wd and “divorced” 4wd applications.
Required Options
716001 Large Hole Retainer or
716002 Small Hole Retainer
Bill Of Materials
