I just bought a 91 civic and it has a d16y7 swapped into it. It had what I am thinking to be the stock 5 speed 91 trans (SL3) that blew and I was wandering. What trans can I use that will fit in the 91 with the d16y7 swap?

 

You should be able to use any 89-91 crx/civic 5-speed transmission. Assuming your blown transmission is from your 1991 civic. The 88 crx/civic has a 21 spline input shaft, whereas the 89-91's have a 20 spline shaft.