Dallas: I have never knowingly looked at a ZF transmission in a bus so I asked the question because of the angle change after the 4104. Your description sounds like a rear axle change would be required to use a ZF.
Stan,
In the one I mentioned, yes, it would require an axle change and modification. The nice thing about that,though, is the axle could be any standard "T" drive axle.
The other thing I've found is that ZF makes angle drives for about any configuration. One of the most popular seems to be the 80° for transit coaches.
I looked at a few of ZF offerings at GATS in Lousville, Ky a few years ago, and pretty much they can take any of their transmissions and put about any of their angle drives on them (within reason). This makes a lot more sense to me than Allisons idea of building the angle drive integral to the transmission.
I still haven't found the website where I saw the 90° drive, but I'll look some more tonight.
Dallas