Ive been told that i can only put a 1996 or '97 transmission in my 1996 Blazer 4wd. Can anybody answer why that is so?

I discovered this morning that part of my transmission housing is broken.The collar that holds the bushing for the output shaft is broken off where the snap ring holds the spring pack in. I had noticed aluminum particles in the pan when I changed the oil, and after having various problems I decided to pull it and rebuild it. When I had it on the ground I discovered it was out of a 96 GMC, the wrecking yard numbers are still on the top.

So, I have all the guts for it on the bench and the kit sitting there too. Im hoping I can get any 4wd 2 piece 4l60e transmission and convert it to my blazer with the correct parts.

Is there really that much difference in them? If there is not, should I be looking for a specific year/model core that will be better to put in. What parts must go into a newer transmission, if any? Cores seem to be somewhat abundant and if I can put an updated transmission it I certainly will.
Any help is appreciated

 

There were several changes made in '96 and then even more that hit in '98. Parts do not interchange, nor do the control methods. If you want specifics, pick up a copy of the ATSG 4L60E Update manual.

 

Thank you. Ill look into it.