Anyone know if all the first gen tranny's are the same? Will a regular 1st gen tranny bolt in? driveshafts the same?

 

A regular '81-85 tranny will bolt in. '79-80 will require finagling with the floor because they have a different shifter position.

5th gear is shorter on the 12A trannies. I personally consider this to be a good thing

 

Or u can mod the tranny, one of 2 ways, like I did to put an '83 in my 3.

 

The 12A tranny will bolt right in the GSL-SE. A friend of mine has one in his GSL-SE. The only differance that I can see other than the 5th gear ratio that peejay mentioned is that the GSL-SE trannys bellhousing has a vent on the left side.