The official,unofficial guide to transfer case adapters

[1-tonmudder]

"What does this adapter fit or what adapter do I need to run transfer case X behind transmission Y" is a commonly asked question on this board and others that I frequent.This is a guide to help identify what parts you have or will need when swapping transmissions and cases.

Starting in around 1970ish until around 1977 the Th350/205 adapters used a center support bearing around the drive sleeve to hold it in place.

The sleeve had a step cut in it to accommodate the bearing,whereas the later style didn't.
Early style on the left,later on the right.



The 78ish to 80 Th350/Np205 adapters are identical to the earlier style with the exception of the sleeve and bearing.All Th350/205 will have a four bolt pattern on the trans side.


And racetrack or figure eight pattern on the case side.


During that time GM also offer the 203 fulltime case behind the TH350's and they took a different adapter.

Trans side.


Case side.


The Th400 adapters came in four different styles depending on the application.
The 400/205 adapters were either the figure eight/racetrack pattern up until about 1984,or the later round pattern used until around 91 when the body style changed on the 1-tons.

Figure 8/race tack pattern (trans side).


Case side.


The late style round pattern adapter.

Trans side.


Case side.