Driveshaft Curiosity

[palposity]

A little background first: I had a guy change the front seal on the tranny about a year ago - well before I decided to do a restoration on the truck. When he dropped the tranny he noticed the U-Joints were bad so he replaced them. When I got the truck back it had a shimmy above 45mph. Since I mainly only plow with the truck I don't often drive it that fast so it wasn't much of an issue. I was always suspicious that he did something wrong w/ the U-Joints though.

Now fast forward to today: So the rear drive shaft for my "Cletus" project was not in great shape. Lots of rust and corrosion around the yokes. I took it to a local "Fleet Pride" shop that specializes in drive shafts and machine work. The first thing they noticed was that the groves for the C-Clips had corroded away so badly there was not a good way for the clips to hold the U-Joints on center. (Hence my shimmy problem). The odd thing that he noticed was that the section that slides into the back of my transfer case appeared to only have about 2" worth of it that was actually in the transfer case. He had me measure from the end of the transfer case housing to the center of the saddle on the rear diff. He determined that my drive shaft was 3" too short! That was disturbing.

Here's what I am betting: I know the tranny was swapped with a used unit before I bought the truck. I am also suspicious that the NP208 that is in my truck is not stock and maybe was not standard equipment for the 86 K20. Anyone know that for sure? I bet the tranny was swapped with a used unit that had a shorter tail housing, and a different transfer case...and I further bet that this was done without changing the drive shaft. Clear as mud???

Sorry for the long story - I just wanted to think this through and share it so any of you who know about this stuff can tell my if my stream of logic makes sense or not.

Thanks guys!!!!