91 International 7100 Spicer 5 speed to 8LL swap

Good morning! First post, so I apologize for the novel below, but trying to make sure I get all pertinent info in.

I have a 1991 International 7100 DT466 with a Spicer es65-5d 5speed transmission with a single speed rear end. Truck is GVWR'd at 33k lbs and I have my class A. This was originally a Coca cola bobtail in Georgia and somehow made it's way to western Pennsylvania and was converted to a dump. It's in pretty good shape. I bought it for my small two-man excavating company and we decided to put an 8LL in to help when climbing some of these back roads in WV to get stone to our customers. I bought a rebuilt one for $2K that came out of a DT466 truck and has the right bell housing.

I've done engine swaps and builds on a lot of vehicles, but this is my first time doing something like this with a medium duty truck. I know there will be surprises along the way but hoping you all can help with my first two issues.

First, my current PTO mounts on the driver side of the 5 speed and the 8LL has a heavy PTO mount on the bottom or the standard mount on the passenger side. If I mount my PTO on the passenger side mount of the 8LL, the hydraulic pump won't clear the transmission case at the rear.

Is there a way to adapt my existing PTO to the heavy duty style mount on the bottom, or space the PTO away from the trans on the standard mount to clear the case, or do I have to come up with a propeller shaft setup from the PTO to the pump (like some Army 5 ton dumps have)? There's a pic below of the PTO and pump setup currently on the truck. (I've since converted it to air shift and air pump controls and fixed the leak in the pic.)

Second, has anyone done something similar and found a way to adapt the speed sensor on the trans to the instrument cluster in this truck? My cluster has some solder issues, but I'd like to keep the factory one if I can. It's the older style cluster. I'm confident I can build a cluster if necessary but expect that to be expensive and time consuming.

If anyone has some good advice I'm all ears. I'm here to learn and hopefully be helpful. Thanks!

Welcome!
There is a bottom plate adapter that should mount that PTO to the bottom. Get the number off the PTO and transmission. Call your local PTO supplier. They should be able to tell you for sure and if the speed is still compatable with your pump.
There is also an offset adapter for the side. It may change the direction of rotation. The pump still may not clear.
Need to use the clutch that matches the transmission. Single or double disc. With or without clutch brake. Probably double with a brake.
Is your current speedo electronic?

Tenwheeler said:

Welcome!
There is a bottom plate adapter that should mount that PTO to the bottom. Get the number off the PTO and transmission. Call your local PTO supplier. They should be able to tell you for sure and if the speed is still compatable with your pump.
There is also an offset adapter for the side. It may change the direction of rotation. The pump still may not clear.
Need to use the clutch that matches the transmission. Single or double disc. With or without clutch brake. Probably double with a brake.
Is your current speedo electronic?

Click to expand...

Thank you for the reply, sounds like I may be in luck without having to buy another PTO.

My speedometer is an older style but is electric. I snapped a picture, it's the large square gauge on the right.:


Really appreciate the help!

I don’t know what brand your current PTO is. Municie and Chelsea both have nice website tools where you just plug your information in and it tells you what fits. That’s what I do instead of trusting the parts guy. I have a feeling it won’t swap over to the 8LL.

https://www.munciepower.com/softwar...jxCbdKUleL1GUldA4cg6OlmFPqKOgSjBoCfIUQAvD_BwE

Thank you for the link! I have a Muncie on the truck now but didn't get the model number off the transmission tag before I left the shop. I'll try to get it tomorrow and plug it into the website and go from there.

I worked for a trucking company back in the day. The first 8LL they bought had the H shift pattern. They ran 359 Petes with 13 speeds. The 8LL was the first 379, and the first 425 Cat. With 373 gears and big rubber, it would go 136 miles an hour without breathing heavy. You never used 8th gear as it was too fast for regular highway speeds. I think the next truck went to 411 gears to function like a regular truck. Unlike the first truck, it had great starting power in deep reduction.

I felt spoiled at my old company in my 18 speed ISX powered Coronado running 75-80, can't imagine rolling a truck at 136. That's the stuff dreams are made of if you can get by with it.

Talking to an old co worker, I guess the 136 mile an hour truck had 3:55 gears, the next one had 3:73, and then they went with a 4:11. I asked about the 136 mile an hour as being so specific. I guess that is what the speeding ticket was for. He was trying her out empty and got caught. Now knowing the kind of BS he used to spew????? I do know it was fast, but I never tried her to full speed myself. I can't see them letting him drive away with that kind of violation.

Coaldust said:

I don’t know what brand your current PTO is. Municie and Chelsea both have nice website tools where you just plug your information in and it tells you what fits. That’s what I do instead of trusting the parts guy. I have a feeling it won’t swap over to the 8LL.

https://www.munciepower.com/softwar...jxCbdKUleL1GUldA4cg6OlmFPqKOgSjBoCfIUQAvD_BwE

Click to expand...

Thanks for the link. I have a great parts guy.

Not sure whether to start another thread or update this one, but going to update this in case anyone else ever searches for it.

Truck is now driveable with the RT7608LL transmission but still needs some things hammered out. I did wind up buying a brand new 8 bolt PTO to mount on the bottom. It was less than a thousand dollars and was the easiest solution. I can't complain because now I have a freshly rebuilt transmission and a new air shift PTO for under $3300.

The driveshaft had to be cut down a little and the flywheel was machined for the larger pilot bearing. These were the only modifications needed to stab the transmission. Still figuring out the speedometer and the clutch linkage.

One of the guys helping me work on it was able to hook the clutch linkage up as in the pic below but the pedal is now incredibly hard to use. It's the same clutch/pressure plate I had before and wasn't bad. I think that the issue is from the clutch bar being pinned at a higher point on the arm coming down from the pedal linkage which changes your leverage, but not sure. The problem was that it won't clear the frame in the original configuration. Considering heating and bending it. The clutch is adjusted properly in the transmission but the pedal is a workout. I would appreciate any suggestions. Pictures of the linkage below. I'll gladly take any other pictures that would be helpful. Thanks!

Last update to this project as it has been finished and back working for several weeks now. Just wanted to be sure I updated this as a reference for anyone who may search it later.

Clutch linkage: Turned out to be simple. This transmission came from a Ford truck and used a very short aluminum lever. Swapped out for a longer clutch lever from a junkyard and got everything working properly. This picked the clutch linkage up higher at the transmission end and took only a little filing on the transmission shaft to fit. I got my lever out of a pile of them at my local junkyard, but hard to say what it was originally out of.

Speedometer: Gauge turned out to be accurate with the sending unit this transmission had in it when I wired it to the wiring harness in my truck, no modifications necessary.

This project was WORTH it in every way, and now that it's complete I could do another simply. This transmission really woke up this old workhorse. I hope this is helpful for someone else.

Current project is swapping an interior from a 1997 4700 into this truck. Have the seats, headliner and overhead console installed and have started on the dash, but that's another thread.