Hi I need some info on converting a 1990 c4 auto transmission into a manual transmission, how hard is it? How much will it cost? And can it be done at home? How much do shops charge ruffly? Has anybody done this, can you post info on it? I have experience with cars but new to vettes, I mainly work on VW'S  

That's a very big job. G.M has discontinued most of the parts you need so the best way is to find a parts car with a manual trans. The clutch and brake pedals will bolt in. You will have to cut a hole for the shifter in the floor pan but the rest is just bolt on stuff. The only problem i can see is the ECM is different. the manual has the skip shift mode. Not sure how to get around that.
David  

Has anybody done this? It's hard to find a manual c4 that's  why I'm thinking of doing this, there is a lot of cheap automatics out there and the only manual c4 that I found got sold before I could write the check($4,200+tax/lisc)When you say the ECM is different what do you mean? Explain please