I agree with 1200rallycar on two points,

1. there are far better places to spend your $$ and time than on fitting a rack and pinion, what's wrong with your original that warrants overhauling? is it out of adjustment? if so let me know and I will advise you how to get more adjustment out of it.

2. Stay far far far away from locked diffs if you are starting out, I've been driving
rallycars for close to 25yrs and I have seen some very accomplished drivers come to grief simply because of the locked diff, if you are starting out - if you can't get a lsd do what 1200rc has done and get a phantom grip, if you can't do that stay with an open diff.

My 'now obsolete' 2cents worth - strange, when i started rallying in 1984 2cents wasn't obsolete...