Dana 21 swap?
I have a 76 F-100 with a 390/np435/dana 21. As most of you know the dana 21 is a single speed t-case, so I would like to change this out to a t-case with low range. I was thinking about a dana 20 out of a bronco, but am not sure if this would hold up to the abuse of the 390. I'm looking for something that will bolt in without the use of an adapter. Anyone out there done this or have some ideas?