Just ran across this on ebay, they are for a city bus and they are axel mount but you would have to check if they would in fact fit your bus. They look like the GM axel mount, they are 492's, and they look like they have the correct angle on the input shaft. You would need to check the length of the output shaft, its hard to tell from the photo. > http://www.ebay.com/itm/301622725454 (http://www.ebay.com/itm/301622725454)
The 492SAX4R cross references as a FLEXIBLE BUS gear.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi.ebayimg.com%2F00%2Fs%2FNDgwWDY0MA%3D%3D%2Fz%2Fqo0AAOSwrklVSitf%2F%24_12.JPG&hash=a33eb6d4062ba3ddbb1776a62ad52e8ea8e59962)
I put a flxable steering off a 1982 870 on my 4106. It fit with pitman arm and all. I changed steering drive shaft and front air tank oh yea, I also changed the power steering pump. I have not changed the angle box yet but it works fine as is. olebusman
The 492-SEE-5A from a GM RTS with the 18.4:1 ratio is a good replacement if you are going to use the Sheppard and with the Vickers VTM 42 clockwise pump than runs on 1450 to 1550 psi the wheelchair equipped will have a 1750 psi control valve