[Power Hungry]

The 250 HP tune will put your engine torque in the 570 Ft./Lbs. torque range. (These are flywheel numbers). Unfortunately, the AT 545 is just not rated for that torque output. You have a bit of an advantage being a smaller and lighter bus, but the long term solution is what you've already indicated... Replacing with a later transmission.

The MT 643 is rated for 640 Ft./Lbs. and would handle the power output nicely. You could also look at going with a heavier Allison MD 3060, which is good up to 1250 Ft./Lbs., but that would require a number of changes including PCM and any associated harness. The big issue is that the AT545 is an SAE 3 bellhousing and the MT643 or MD3000 series is an SAE 2 bellhousing. This would require conversion of the engine to transmission bellhousing adapter. CadillacKid on the Skoolie.net forum would be able to help advise on that one.

Here's a good page describing the differences in bellhousings. https://www.sbmar.com/articles/under...-measurements/

I'd say at this point you may want to just keep it at 230 for the time being. Nobody wants to replace a transmission unless absolutely necessary, and we want you to be able to travel reliably.

I hope this is helpful.