My third gear syncro has gone and I really don't want to spend huge money to take it in. How hard is it do replace the syncro myself?

 

Once the tranny is out of the car you can have it all apart in about ten minutes.You will need to look at the parts very closely for how much wear they have.Just changing a single syncro will only help for a little while if other parts are worn out.There are a lot of how to's on transmissions for reference.

 

is there such thing as a tranny rebuild kit...?

is it most likely for me to get confused or if I follow that thread on how to rebuild a tranny I think I should be fine.