What dana 20 is this?

I have two dana 20 t-cases. One came from the back of a T-15. Can you guys tell me what the other dana 20 came off of?

 

The one on the left is off of the T-15. The one on the right is the one I am curious about.

 

Do you guys see why I am asking about this one? Look at the slots that are machined out of the housing where the t-cases adapt to the transmission. They are different. That is why I am asking if anyone can tell me what the t-case came off of that has the slot missing underneath the bottom of the hole the output gears of the tranny go through. Your help is greatly appreciated.

 

Brings back bad memories for me. I ran into the same problem. That "slot" accommodates some rails that protrude from the t-15. When I had the tera-low put into my d20, i bought a used onw, not realizing that I needed that cutout. I ended up having to go to a machine shop to get that added to the new case. As far a I could tell, the d20 without the cutout could be from either an auto cj7 or a t18, or some later transmission. After I had the slot machined, the case fit perfectly. I suspect that the slot might be unique to d20's that came behind the t-15.

As an aside, I'm curious about something that you might be able to help me with. Most D20's have 10 spline output shafts. When I swapped cases, I found that my new d20, the one without the slot, had 28(27?) spline output yokes like a d300. This is not common on most d20's, and as far as i know, the 28 spline outputs was usually attached to the autos, or the very end of production d20's. If you happen to take the yokes off of yours, let us know the spline count.

 

The Dana 20 that came with my t-14 when I bought my 72 also has that area milled out.

 

Can you show a pic of the shift rails and linkage? That may give some clues. Most likely though its from a T-18 or an automatic. Some of the automatic units were flat with no cutouts whatsoever and some had some cutouts.

 

The 28 spline were built toward the end of the run. I read that they were cheaper to build but no stronger.