I have a 75 f600 ramp truck, was an ex U-Haul truck for delivering the rental equipment, so it got the good stuff since it was not a rental, 359 4v, 5 speed and a 2 speed rear, it has been turned into a ramp truck. My problems is it has a 6.33 gear, I never use first, and rarely 2 low, most of my time is spent in 4th or 5th gear even on the hills. I have a 5.83 to swap into it but was wondering if there are any taller options. I'm running a 9.00-22.5 tire and don't want to go any taller. Overdrive would be nice but seems impossible to find. 55mph is a stretch right now, would love to run 65 or 70 with it as I use it a lot. Would be nice to keep up with traffic.

 

I use the calculators here as they are easy imo, and allow a number of variables.

https://www.novak-adapt.com/knowledge/gearing/

It appears the loaded diameter of your 9-22.5s would be 36". Even with your 5.83s you are looking at 3000 rpm at 55 mph. (this also assumes 5th is direct)

How is the gear spacing on the 5 speed if you start out in high range? It will only deteriorate with a taller gear, and unless you find another 2 speed with that (or a taller yet gear) as high range, it will be miserable in hills at certain speed.

You have plenty of room for an auxiliary trans or "brownie". There is a thread about those and I'll post it when I find it.

And here we go. You will have to sift through it as a lot of it is not going to apply to you.

https://www.ford-trucks.com/forums/5...ie-thread.html

 

gear spacing is a close ratio, it works great on hills as it is, but I never need to go any lower then 4th low, seems I could make better use of the lower gears with a taller axle ratio. 1st is just for putting around the driveway, even on hills I take off in 2nd with a full load. With a load on flat ground I usually take off in 2nd hi, or 3rd low. it's a 15,000 eaton, don't know the number, the ford bood shows a 5.33 or something near that but I have never seen one.

 

5 speed OD's are out there keep ya eyes and ears open. Myself I'd stick a auxillary
in there with, 3 or 4 sp. with OD., little driveshaft work end of problem. I know '0'
about 359's or its family cause I was thinking to go AOD. If its in the 460 family those
are dime a dozen but I don't know. We put a powerstroke with AOD in a 49 F8 runs
like a champ that came from a 199? something F350 toasted frame for barter.

 

The 359 is basically a 361, brother to the 391, ft series, same bellhousing as the fe. Thats a nice rollback, thought about putting a cummins in mine with the zf5, put the gear ratio would kill it. Don't want to have to do alot to the truck for now, down the road it may be going on a late 90's f800 chassis with air brakes and all the modern drivetrain.

 

Nice trucks! Mine has a Rockwell H170 single speed with 7.17 gearing - so I feel your pain. Leaving from a red light you can be in fourth gear before you are through the intersection, and that only leaves fifth, which you use as you pass under the lights on the other side of the intersection.... you get the idea! All of this means that an engine that was not designed for high rpm has to do high rpm if you are going to keep up with the flow.

With 5.83 ish gearing and the tall tires I think that a diesel with overdrive would be ok - I might be going that route myself someday. Trouble is that even if you can get gear sets for these axles they tend to be very pricy. I am watching out for a complete axle to swap in that has the ratio I want. I believe some large truck axles are 4.10 but you would have to swap the axle to get a gear that tall. You may find that the 359 is lacking in torque to handle that ratio (if it is anything like the 361)

Correct me if I am wrong, but I thought that the bell housing was larger than the FE.. my understanding was that the 360 and 390 had 11" flywheel/clutch and the FT series 361 and 391 had 13"

 

It is a much larger bellhousing on the ft, but same bolt pattern, just does not taper down as much. I have a 3.55 single speed out of a newer truck, way to tall when loaded for me, something in the 5.33 or so range would be great with the 2 speed. I have a ford bus chassis with a 5.9 cummins, auto, and 4.88, direct, it tops out at around 58, still kinda slow.

The ft's are fine running against the governor all day long, thats how I run mine, never had a problem, but they are also lower compression, very heavy duty cooling, and governed low enough you won't hurt em, but 65 or 70 mph would be great. They don't like me on I-95, technically it's not even legal because it won't run the speed limit.

 

I have a '58 F600 that originally had a 292 Y-block, 5 speed (DD) and the 2 speed Eaton with the 6.33 gear. It is more of a play truck than a work truck and at any speed over 50 mph the engine was screaming. I went to a truck salvage yard and the guy there said Eaton never offered a ring & pinion for the 2 speed with a "higher" ratio than the 5.83. He said they did make a single speed with a higher ratio and the entire differential will swap into the 2 speed housing but they are rare as hen's teeth.
I finally decided to bite the bullet and I bought an '89 F350 with a 7.3L IDI and the ZF5 (OD). I found a salvage yard that had a Dana 80 rear axle with the 6x8.75" bolt pattern and 3.73 gears. I also found a 3 speed brownie in another salvage yard.
It is all together now and it suits my needs. With the brownie in UD it will pull a load and in OD it will go down the highway just fine. I have 9R-22.5 tires on it.

 

As I understand it the 359 is a 361 with a cast iron crankshaft instead of forged steel and was made specifically for U-haul.