[bilfman]

I have 32" tires in my 4l80 swap and run 3.73 gears this spins me around 1850rpm at 60. A little low for my liking but I just completely rebuilt both front and rear diffies this past spring so I'm not going to open them up just yet. I think 4.10 would be my minimum with 32" tires, money not an issue, that would be for my liking.

So for your question, with my 3.73s, 32" and od it is just fine for cruising. But when I pull the big boat I find myself needing to shift to 3rd occasionally. I am currently redoing some 781 heads with a bigger exhaust valve and roller rockers. Also switching to a stouter lower rpm cam to bump my power and torque for pulling to help 4th towing out.

So I am thinking with 35's 4.10 or 4.56 is the way to go. I had 4.56's before I had the 4l80 and wish that I had that back.

Hope that helps.