Why not just install a bronze tipped 'load bolt' like Gapp/Roush and all the other Pro-Stock guys did in the 70's? When the ring gear tries to push back from the pinion it touches the 'load-bolt' and STOPS. If it was good enough for Roush, Glidden and Scott Schafiroff it should be good enough for me. Plus you save all the nasty unsprung weight.

 

ok..a little input for you guys here...i did a tko 500 swap into my 2003 mach 1...(originally a 3650)...anyways the debate over tko 500's and 600's.....the tko 500 is going to be better for a couple of reasons....for one it has a lower 1st gear ratio so not much rear gear is needed to accelerate the car...2nd you can buy a tko 500 with a 26 spline input shaft JUST like the tko 600....the tko 500 is geared for better accelration...NOW the tko 600 is set up for a car that has alot of horsepower so it can take off easier (less 1st gear)...when i say high hosepower cars, i'm talking about a turbo or supercharged car making a BUNCH of power...the tko 500 is the way to go and you wont be dissappointed...i had one in my '03 with 4.56's and cruised 70 mph at 2800 rpms....so in a light car like our 66's you can get away with a 3:50 gear no problem and probably only rev about 2200 rpms at 70 mph