I have a 99 Blazer with the auto 4wd option. Can I swap the transmission from a 97 that doesn't have the auto 4wd?

 

One difference on the transmission side of things is that the 97 may or may not have had a two piece main transmission case (removable bell housing) and you 99 definitely has a two piece main case. The bolt pattern on the back of the transmission may also be different (square 4 bolt pattern vs the hex 6 bolt pattern your 99 has). You have to check and see. Other than that, the transfer case used has nothing to do with the transmission.

 

the output shaft on the 2wd is longer then on the 2wd so you can use it only if you swap the shafts out which means taking the tranny apart....