I have a 1997 GMC Sierra Z71 with 350 Vortec motor and auto trans... I also have a 1999 S10 blazer 4x4 with 4.3L Vortec and auto trans. So the question is, are these two transmissions the same? Im scrapping the blazer (bad motor and parted it out) and would like to pull and save the trans if it is. Thanks

 

They both should be a 4L60e
Best thing to do is get under there and look at the part numbers
Even thought the internals may be the same the wire harness or fluid cooling line hook ups maybe different

 

Even though it will bolt up (assuming they are both 4L60Es) the gearing is likely different.
The stamping numbers would need to be identical to be 100% sure they are geared the same.
I would think a Z71 8cyl is geared different than a V6 Blazer