I get these bright ideas every once in a while, and my latest one is to possibly install a 700 R4 overdrive trans in my stock '71 GTO presently with a TH400. I'm running a 3.55 posi which I like a lot. Just trying to cut down the rpm's when cruising 50-55 mph. I'm sure others have done this. Are you happy with the results?? Would you do it again?? Much work involved?? Parts needed other then the transmission itself?? Thank you.