Have a 86 1 ton 460 4x4 currently has stock 3.55 gears with 35” tires. I never hauled a loaded trailer with it in that configuration, and since switched to a 35” tire. Engine has been warmed up a bit since then, but still don’t have a granny gear, or the ability to stay in a particular gear on decent incline. I wanted to switch to a 4.10 ratio which is the equivalent to stock set (3.55 with 31”) vs (4.10 with 35”) I find myself shifting from 3rd to 2nd on inclines around 45mph with a loaded trailer, bringing revs up pretty darn high. The cam is all in at 4500 and was told I would be better off with a 3.73 because of highway speeds (70+) unloaded. I hate the fact that I have to downshift a rather powerful engine combo just because of the gear ratio, but now I’m unsure of whether the 4.10 is the best option. I have the front gear set in 4.10 all ready to drop in, so that scores a win in that category, but I’m rebuilding the rear with a Detroit truetrac, so I’ll need the ring and pinion, install kit and carrier. Most of my heavy hauling is 65mph max and maybe faster empty, I know I need a gear swap, but only want to do this once! I don’t sit to gain much with fuel mileage with a 3.73 over a 4.10, but it’s rather important I keep the t-19 in its powerband.

The only reason I didn’t think 4.56 was because of the carrier break at 4.10 ratio on the front axle. You’re right, I don’t have granny or overdrive with the current setup, may as well choose one or the other!

I thought by hopping up the 460 would cure that problem, but it really didn’t. I’m either bogging 3rd gear around 1200rpms or screaming 2nd gear at 4500rpms on a small incline 35mph loaded. Hopefully the gear swap will cure this! Good call on the zf, I’ve been looking for many years for one in my area, most all are 2wd, and for the 7.3. Maybe someday.

ive decided that it’s not a highway cruiser, so the lower rpm at highway speeds aren’t as important, I’d much rather have the low speed torque.

Zf5 or zf6 or even the t-19 with a gear splitter are all very nice options and are high on my WANT list, however, none of those options are in my price range or available right now.

I was only looking to raise the rpm of each gear at the same mph to keep it in the powerband better. I agree, the t-19 is not the best transmission due to wide ratio and no overdrive. Based on my example, instead of having to downshift to 2nd, I will have a higher rpm in third to hold the hills. I will sacrifice top speed at the gain of getting granny gear back (I’m currently using it as a 1st gear and can’t crawl unless the t-case is in low range).