Definitely go with the 5 speed, the overdrive is great if you're going cruizin' as it allows you to run a deeper gear in the back and still go play on the freeway at a decent rpm..... Depending on your horsepower, might want to step up to a TKO, either a 500 or 600. Mike Forte advertises on here and has a ton of experience plus all the goodies you'll need to make it a simple conversion!!!!!