What rebuild kit to buy????
If your guy knows what he's doing he'll tell you what to buy.
I NEVER built a trans with someone elses parts. If their selection of parts fails I have to fix it for free, or I did something wrong.
Ask this guy what he recommends, if he doesn't have an answer move onto someone who does.
There is a big difference between a transmission builder, and a transmission assembler.
Almost sounds like you're dealing with an assembler by the way you put it.


