When I went 5speed . . . . . . almost everyone said to me that I should Change rear gears .
That I would like a .. 3:50 - 3:70 gear a lot better . So I just left my rear alone (with the p/g
stock rear 3:08 gears - with my T 5 1st gear at 3:97 . o d gear is 0:72 .
So far , it's been great with my 'little 250 engine' …. ..
jim . . . . . . . . . "still shifting" …… (bigallis - Jim , over two years , now ) ……. vroom .. vroom
I went with 5 speed, LS in my 63, it fit, but had to do some massaging, its a tremic 5 speed, I got from Liberty gears in Detroit, they do machine outer casting for better fit, I am running a bunch seat, so console not a issue, but shifter comes out more in middle of tunnel, sure it work, but probably have move console brackets,
I'm thinking that the only way to not alter the tunnel is to go with a Muncie. Tremec definitely needs some tunnel change, I think Nash does as well, as do the S-10 swaps in a '62-'67 car. The other thing you need to consider is the shifter location, and if that's too far rearward for your seating. There are a ton of threads here on SNS if you want to use the search bar about fitment of transmissions in these cars, I just don't remember the thread titles.