Hello I have a 71 RS with a 454 and 410 gears I'm looking for a trans that can cruise on the highway. I have a M21 muncie now and it's just not getting it. I live in Lake Havasu and I don't take it out of town, it needs another gear. Don't know what the gears are in the trans but 4th gear is about 50 just cruising, how ever to bump it up to 70 or 80 the motor would be to high of an RPM. I was looking into 6 speeds, but from what I've seen it looks like a big dollar nightmare! Plus I wouldn't be able to use my skatershield! I had an uncle that raced at irwindale and he had a clutch come thru the floor and almost cut his right foot off, After seeing the car and how easy it cut thru the floor, I want to keep my skatershield I want to know more!