T56 = 80mph @ 2260 rpm
 

Update on speed and RPM, I'm able to cruise 80mph @ 2260rpm in 6th. 325/30-19's 26.68 diam with 3:55 gears.
Looking back, i'm so glad I went with the T56, the 5th & 6 OD have been amazing and very useful. Of course I find myself in 5th a lot around that 60mph zone and that's exactly what it is for. I did 110 miles yesterday, mostly interstate and cruising 80mph in 6th was nothing short of euphoric 💖

Hard to go back to the old days without overdrive and 3000+ rpm's on the freeway (and that's if you're only doing 60 mph lol).

I remember having a 3peed Saginaw behind my 350 in my 68 Camaro (ex 6cyl car). Driving back an forth from NJ to college in Delaware. Sucked on highway. Glad gas was cheap… Couldn’t wait to put a 4spd in it. Once I had the 4spd thought I was in heaven. Many years later put a 5spd in my 68 and it was awesome having that extra highway gear. Now having a t56 in my 67 it is a great trans for all the torque our cars make today. Along with the gears for the highway and helping with the gas mileage.

I have a Tremec 6 speed in my 34 3 window coupe. It has 4:56 rear with 30" Firestone's. I drive in town in 4th. On the highway at 50 mph (1800rpm) in 5th and not until I'm on a freeway slip it in 6th. Pretty much perfect for the application. In this car the only time I would be going over 100 mph would be 1/4 mile.