It seems like 13 speed transmissions are either double low, or double over (drive)? Is there any that is just one of each? Or maybe that is what you do with the double-over one?
Simp says the 654 tranny is rated to 950ft-lbs. The ISL engine is torque limited to 1200ft-lb even, per request of Allison trans limits. I'm hoping 950 and 1200 are close enough, considering it will always be an empty truck. If I do bust it, which would be a shame because it is a butter smooth shifting transmission with zero leaks, another auto is not going in there. We are going to be rowing gears one way or another.
Tranny choices so far are the stock Allsion MT654CR 5 speed auto, the stock RV Allison 3000 MH 6 speed auto from the motorhome the ISL was in, a 6 speed manual Eaton single countershaft from an 8.3L powered Freightliner with an 8.3L, or the 13 speed grendel threw over the fence, supposedly a double low (LL) type deal.
The more I learn, the more I discover I don't know, about anything...