I have a 69 Firebird with a three speed HD all original car down to the Block. Want to put the three speed aside and run a 4 speed for a while. 3.36 rear gears factory 10 bolt.
You guys should see this car it’s all original never been messed with with 20,000 miles on it. I got it out of Montana even the original air filter was in it original battery everything eight track player total time capsule I’ve never seen one not messed with ever. Did phs All original car, and 69

That sound amazing. A three speed manual was basic stock trans unless you upgraded. What kind of three speed? I had a 1967 400 parts car and it had a Borg Warner T-16 three speed. 3:55 rear gears. That became my spare trans when I would damage a four speed. I never could harm that tough-azz three speed. Whatever four speed you choose, make sure you have a good match up of first and rear gears. Too little gear, you will be riding the clutch just to get going. Too much, and you will be starting in second gear. I like to see a ten to one overall ratio for city street driving. Muncie ratios are limited. A 2:20 close ratio will be only 7.4 to 1. A wide ratio 2:56 gets you 8.6 to 1. The Super T-10 has a much better selection of gears and is much easier to find. Stronger too.