transmission problems

[lilbanger]

I have a 91' 240SX with an auto transmission, I just recently bought the car from a friend, thinking I could fix it. When I bought it, he had just put a trans in it, cause it wasnt shifting. I drove it home in first gear, and it had a knocking sound, come to find out the flywheel was broke. So I snatched the trans put in a new flywheel and another trans, and Now the same thing, NO SHIFT. The car will go forward in 1st gear and has reverse, but it is not shifting, acts like it wants to shift but it doesnt. Another friend told me to change the speed sensor, so I did, and, nothing. I have some wires that are stripped back that come from the speed sensor and are wired to the main harness beside the under hood fuse box, (yellow/blue wire going to red wire, yellow/black wire going to white wire) are these right? Or am I just not getting something right here??