Re: Info on a Thomas type D School bus
Well...to further the hijacking since this thread seems about dead unfortunately....
My bus is a 65 passenger. It's in essence a 66 passenger, but the rearmost seat was ordered narrower so it could fit a garbage can and not block the emergency exit. See what I mean about each bus being speced differently for each individual order?
I have a 6.6, but I have an AT545. I think it would be possible to find one with an MT643 as it certainly was an option, but I think you're going to have a hard time finding one. A 4+2 or 5+2 manual is probably going to be MUCH easier to find if you want a stalled connection at highway speeds. The AT545 is a good match for the 6.6 though. It has some disadvantages versus the other transmission option, but if it wasn't a good transmission it wouldn't have been used to 25+ years.
As for handicap accessible...well...that's another hit or miss thing. I'm sure they're out there, but it might prove to be easier to modify a non-handicap bus.
In reality, your ideal bus is out there somewhere. I know mine is pretty darn close and nothing that you listed is the least bit out of the question. It's just a matter of finding it...