T221 to NP205 swap guide

[Tito19]

This is my guide/experience with swaping the Rockwell T221 for an NP205 in to my 1969 K20.


1) NP205 transfer Case w/ adapter. Adapter shape varies depending on your transmission. My Trans is a SM465 so my adapter is the figure8/ race track/ peanut .ect shape, people have different names for it. I put new gaskets and a coupler before putting it in.

[Tito19]

2) Transfer case Crossmember. I used the stock T221 crossmember. You will need to re-drill the holes through the crossmember into the frame rails due to the length of the new transfer case and adapter. I did this with a 12" long 3/8" drill bit. Using the stock member caused the top of the transfer case to hit the cab floor, so I notched it out. And yes I do have a high hump tunnel and just installed new cab mounts, and it still hit.
2a) I've read that if you use the NP205 transfer case crossmember you will not have this problem. Or you can put spacer between the member and the frame rails.

[Tito19]

Upper part of the crossmember

[Tito19]

3) Drive Shafts. The NP205 w/ adapter is a longer unit the old T221 so you will need new drive shafts made to the length that you need or cut and lengthen the old ones. I went with new ones from Tom Wood's @ 4xshaft.com. I used a one peace rear driveshaft and choped the carrier bearing mount off and it looks like I will need to notch the support beam to clear the driveshaft. The front just bolted in.

[Tito19]

Carrier bearing mount

[Tito19]

No more carrier bearing mount

[Tito19]

If you have not read Yukon Jacks thread no this subject I suggest you look it up. It will help you get a different perspective on this swap.