I have been considering doing a NP435 D20 in my YJ. In my search for parts I came accross a NP435/Dana 21. The D21 is similar to the D20 but has no gear reduction. From what I can tell the Dana 21 looks Identical to an early Bronco Dana 20. It appears that I could just bolt them together accept that I don't have a 20 yet. This seems to easy. Has anyone got any info on this. I hope that this works.
Josh

ANYONE????

I may be mistaken but as I recall the Dana 21 was a divorced single speed tcase that was used in late 50's/early 60's Ford F100's. The Dana 24 was the 2 speed version with a 1.98:1 low

The D21 is indeed the single-speed case you found. I guess Ford figured that the bull gear in the 435 made a low-range t-case kinda redundant...

I have heard that the D20 won't bolt up in place of the D21, but I can't remember what the reason was. Pretty sure the interface must be different at the t-case, or there wouldn't be much of an aftermarket for custom 435/D20 adapters, would there?

Chris
PS: Try the Ford forum.

The pattern on the D21, although similar, is not the same as a 20, that is why it won't work....as Chris said there would not be as big of a market for 435/20 adapters.

And the D21 was also used in 70's F100s as well. I had one from a 74.