More of a medium duty issue...

Allison AT545 are a light duty transmission, they were a great school bus transmission.
The shift points are adjustable. There should be a cable for a throttle valve on the left side of the trans, running to either the foot pedal or injection pump linkage.
That adjustment varies the shift point based on throttle input.
All of mine were adjusted correctly and would shift at up to 2500rpm.
They are a bit of a turd for pulling, no lockup converter and very little engine braking, and only in 4th

 

I like the 545 for driving around town! It's great for slow n go. But yeah a total turd for towing or driving in the mountains. That's really the reason I'm thinking about changing. I can't afford a new rig - I've put so much money into making this one just the way I want it

The super 10 weighs about 50 lbs more than a 910. The 910 is 576, the super 10 is 630, so weight is negligible. The real issue here is that both of those boxes weigh about 2X as much as a 545, so I'm thinking I would need a cross member. Which kinda sucks but there we are.

 

I once owned an older International with mechanical dt466, air brakes, and 10 speed. Not a 5+2, but regular 10 speed. Never crawled under it to look at the tag in the short time I owned it, but I do know they made them like that for heavier applications.

 

I know where one is. The tag is missing. The man would part it out for good money. Truck serial number might tell what it is but do not know it it is original.

 

Some transmissions do not shift easily at higher RPM. You have to learn how to work around that.
Some later S model DT's came with a straight 7 speed Spicer. They were OD in high and shifted like a 1 ton as best I remember.

 

Been 20 years since I had mine, but seems like I remember it not liking to float the gears. Think I ended up double clutching most of the time.

 

So it does have an sae 1 bellhousing, and needs an sae 2. A little googling shows I can get an sae 2, but looking like they're over a grand. Also, I've found the model number to be a rtlo - 14610, 15610 or 16610. The only way I can find out is by taking the aux housing apart and seeing what bearings and shafts I have in there. But - if I can't find a bellhousing for around 500, I'm going to part it out or scrap it.

 

Why do you care if it is a 14, 15 or 16 series? They will all work if you can bolt them up.
Then you need a different flywheel, clutch, clutch core charge, shorten driveshaft, search for yokes for trans and probably front diff. , change the whole front driveshaft, different top plate to get the shifter through the hole? That is off to a good start.
If $500 is make or break you need to walk on!

 

Hit another snag. I found a 14" clutch that fits in an SAE2 ans 2" shaft, and I found an SAE2 bellhousing also. I was thinking I was golden, until I ran into the pilot bearing. From what I can tell, the pilot bearing needs to be a 205SS, which has a .98" bore. The pilot bearing boss for the input shaft on the trans is 1.1". Way too much to be an interference fit. I'll keep on diggin!

 

can you get a bearing that will fit the input shaft and bore the flywheel?