Cummins repower- 8.3L 6 CTA

[Rusty]

Hi all, new guy here.

Did the search, didn't see an answer, so...

I have a few military m923a2 trucks equipped with mechanical Cummins turbo 6CTA 8.3L and Allison MT654CR auto trans (CR is close ratio). This combo easily pulls a 21,000lb empty truck. As I am comfortable working on this setup, would it be advisable to get a clean pusher with a bad ticker and do the swap?

If this is doable, which would make a good bus choice? I realize my setup isn't built for speed, but parts are plentiful and I'd be happy driving 60mph.

Thanks in advance for your input.

[charles_m]

I don't think it's advisable if your primary motivation is because you're comfortable with it.
For example, I have a bus that has that engine in it with an Allison 643--A powerplant so similiar to what you are familiar with, you might as well buy a running bus with that in it already. Its like $5k for a good bus with that setup. You could find a busted one for maybe $1200, but what is your time and parts cost going to be? In economic terms, I've never seen it pay off to buy a bus with a blown motor unless you already own the parts you'll need to make it run and can do the work yourself. But if it's what makes you happy and you dont mind spending your time and $$ on motor work, you should absolutely do it, man!
Just one guys opinion

[Rusty]

I do have a complete donor truck with the cummins/allison combo. I am semi-retired, so time or space isn't an issue. Wondering more about fitment. I realize there would be some plumbing involved, but am mechanically inclined and creative with a big hammer.

[charles_m]

If it had the cummins stock, then it would definitely fit. It is a common motor in RE buses, so it really shouldn't be a problem. If it had something else in there before, it might get tricky. But I bet you could find one with a blown 8.3. Finding a bus with a blown motor AND tranny might be a bit of a unicorn. Swapping in the close ratio gearbox is going to ruin your performance and be a MAJOR bummer--You'll be missing out on all the fun of that 8.3. You'd be better off with a stock MT643. IMHO if the bus has a working MT643 or MD3060, only swap the engine--it will be easier, cheaper, and perform better while being essentially the same trans as the MT653CR in terms of the maintenance required from you. If it has the AT545, I'd swap the trans. But the AT545 is not very common in RE buses, and it would never appear in one that has the 8.3 from the factory.

[crazycal]

Unless the the dead bus is in your neighborhood, the tow bill will be more than the bus. If your a 5 ton wrecker, that's a different story.

[nat_ster]

I'm in the market for some axles out of the military truck.

I say go for it due to most of the military trucks have few hours on them compared to a wore out bus.

Nat