Factory Dana 20 SM465 Adapter?

I stumbled across a deal on what appeared to be a factory GM D20 to SM465 adapter so i bought it and the 465. I already have a D20 that i rebuilt & did the D18 gear mod to so I didn't want the D20 or the GM bell housing that was mated to them. So i get it home and as my luck would have it the bolt pattern on the adapter doesn't match my 20 but the spud shaft does accept my input gear. I can't find any info online about a factory GM adapter of this sort but the transmission guy i bought it from showed me his reference book that list the D20 as being an option behind a SM465 in a Blazer for a couple of Years in the 70s. I don't remember the exact years. Another strange this is the adapter says Rockwell on it. I did manage to snap a pic of the casting # on the Dana but unfortunately i can't load pics from my company phone to my computer & I only snapped the one close up pic. It does clearly say Dana and the # C-8-15-38 or C18-15-38. Hard to tell if its a C-8 or C18. I know most D20s that Ive seen are C18-15-24. So my question is was that a dana20 or some other rare Dana t/c? Has anyone ever heard of this adapter or a D20 with a different bolt pattern?

 

Yes. Odd adapter and case, oddball shifter, and fair warning, the 20 rear output shaft has a unique rear output shaft with a caged Torrington style bearing in a machined recess which is unique to the GM 20 transfer case. We used to get $75-100 just for the output shaft. These were used in the '68-'72 vintage Blazers only. Most common were the 20's behind the Saginaw 3 speed with column shift and also a special adapter.


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Thanks for the info Nickmil. The transmission guy said he would give me that case. Do you know if I could swap the rear output and all my D20 guts into the GM D20 case?

 

You should be able to. If you use this transmission and adapter you will need to use the Gm 20 output. Your Jeep 20 output shaft won't work.


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Novak and advance adapters have a kit of 18&20 transfer to the 465. You will have to possibly clock and grind the side of the 465 to fit up. 465 goes right to GM bellhousing

 

True to a point. The bolt pattern is the same on the transmission side. If using a Chevrolet 90 degree V-6 or V-8 you can use the bell that came with the transmission. If not then the front bearing retainer and the indexing hole in the bellhousing must be machined.