Tranmission 97 GTP

My flex plate broke in my 97 GTP. Since we had to pull the stock tranny. I decided to bulk it up a little. Put in a Thasher switch kit and a smaller torque converter.
Started it up and its missing 3rd gear. Put it in 3rd manually and there’s know difference between second or third. Made sure we put the lines for the shift kit in properly. I thinking it could be grime blocking the line or third gear is completely trashed. I was thinking about a flush but that cost a 100 and it might move the grunge some place else. Also the 100 I could put toward a new tranny.. What does the prix forum think?

Did the transmission shift alright before you put in the shift kit? If so you may have not gotten the shift kit in properly and that would cause the problem you are describing.

Took the Tranny pan off drained fluid. According to the shift kit manuel everything is put in properly. I was hoping it wasn't. Yes third gear was working before the flex plate blew.