SM420 X JEEP DANA 18/20-6 SPL

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

• ADAPTER- SM420 TO JP/SCOUT D18/20 / 51-1201
• SHAFT- GM 10SP/D18-20 INPUT / 52-4700
• MOUNT BLOCK / 716224
• SNAP-RING EXT, INPUT-SHAFT GEAR / 716453
• SET COLLAR- 2 PIECE 1-3/8 2PC / 716454
• GASKET SET-MUNCIE SM420 TRANS / 716508
• T.C. GASKET/JEEP or TOY L/C / 716568
• H.H.C.S. 3/8 -16 X 1-1/4 (GR5) zinc / 723722
• 3/8 -16 X 2-1/2 H.H.C.S. gr. 5 zinc / 723733
• F.H.S.C.S. 7/16 -14 x 2-1/2 / 724342
• 7/16 -14 X 1/2 SH SET SCREW / 724351
• NUT-NYLON LOCK 7/8 -16 / 728701