I ran into a problem while swapping the front yokes and driveshafts from my '79 F-350 into my 77.5 F-250. The outside diameter of the yokes are different, although they are both NP205's. Is this a simple matter of changing the seals to complete the swap, or is the housing different somehow?

The '79 has a heavier looking yoke with a CV joint driveshaft, and the 77.5 has a smaller yoke (and smaller OD at the seal) and has 1 u-joint on either end of the driveshaft

Thanks for your input!

 

Take off the yoke nut and swap them. You don't NEED a new seal, but it is a good idea to change when you are already in there.

 

I think he was saying that the yoke and seal have different sized sealing surface diameters. I would think that it would be as simple as having the correct sized seal, as I don't think there was any major differences between different year 205s. I would remove the seal from the donor case and see if it fits the case you're using.

 

Just remove the entire seal retainer, and bolt it up to the other t-case. Everything as complete and as easy as pie. Remove the yokes, and the aluminum retainer, and bolt everything up, and you are good to go. YOu are just looking at a small difference in yoke O.D.
Keep in mind that if you are running the larger double cardan joint in a truck with an auto transmission, you may have clearance issues with the trans pan. Larger is better until it hits the pan, and causes damage, if it even bolts up. This is a problem with short adapters and large joints.

 

Thanks! That's a great help!