[jhv48]

I had the .64 overdrive in my TKO600 and absolutely hated it. 3.54 rear gears. I’ve got a street friendly 550 horse engine that pulls just fine from 1800 rpm in top gear. I found myself rowing back and forth from 5th to 4th during freeway driving. There was such a big jump from the fourth to fifth gear. Almost 1000 rpm.
Swapped out the tranny for one with a .81 fifth gear and couldn’t be happier. Now I actually have a usable fifth gear. I’m turning about 2500 rpm at freeway speeds and can accelerate smoothly if needed without dropping a gear.
I highly recommend the .81 fifth gear. Based on 35,000 miles of all kinds of conditions.