Re: Flxible bus transmission
most flex transit busses of that era had vs2-8 or the vs2 transmission. some had 6v71 engines and the vs-2 transmission. I have owned both kinds, with the 8v71 with the vs2-8 transmission able to go around 70mph. The speed depends on which rear gear it has also, as many top out at 60 or less. My friends probably bought over 60 at the auction, some were the gm transits, and others were flex's with a few being the am generals. so if your bus will do freeway speeds it's probably the vs2-8 tranny.
I have never had transmission problems with mine, although not only do you have the engine and transmission, you have the planitary gear set which can go out. They are also a lot of work to fix. Other things to be aware of is oil leak in back of engine, air compresser back there and alternator... and the torlastic fan which i assume yours probably has... so you done want high gear noise either on the front or back of the engine...
another thing to check is the ujoints and the drive shaft yokes, as these will cause vibration and you might think its something else.
just thinking... but have had to deal with the above stuff...
Jesus Christ... Conversion in progress.