Transmission recommendation

[HerpDerp1919]

Ive got a 79 thats got the 350 and th350 transmission. However, I would like to be able to cruise on the highway without revving the heck out of it. Its a 4x4, and I do some very light towing, meaning my 16ft boat (maybe 1400lbs total with the trailer), two atvs, and the occasional car as Im the only one on my family with a truck. What would y'all recommend?

[zieg85]

What is your current gear ratios?

[Captain Swampy]

And what size tires? What's the predominate speed limit in your area?

[HerpDerp1919]

i'm 99% sure I have 3.73s. The main speed is 55, but id like to be able to 65-70 without it scrreaming. I'm gonna be putting some 33's on it here in a couple weeks

[K20Detroit]

For going 70, you'd be looking at a 700r4 IMO.
I have a 700R4, 33" tires, I think 4.10 rear gears (missing RPO sheet).
With my diesel, it does pretty good in the 70MPH area. Revs aren't high at all.

For towing; supposedly the 700r4 is a weak trans in factory form. I haven't seen it first hand.
Either way, when hauling or even just driving slow, I pull it out of overdrive until I get up to speed. Otherwise, 4th shifts in early and slows acceleration.
I'd recommend a corvette servo upgrade, it costs about $30 maximum and firms the shifts.

[HerpDerp1919]

Thats what I was figuring was an R4. When I do tow id just pull it out of OD like i did in my 96 Silverado.