It should not be any different from a similar vintage ordinary van, of which there are a gazillion on the road. Finding a write-up or YouTube video about them shouldn't be too terribly hard.
Here is one write-up that seemed reasonably thorough, though I can't vouch for accuracy nor suss out exactly what years it was referring to. It also isn't for an E40D specifically. In any case it ought to be pretty straightforward, aside from the obvious difficulties like the fact that the transmission is quite a heavy beast.
If this motorhome has the driveshaft mounted parking/emergency brake setup, it would also be wise to look up the info on that contraption as well. It's bolted onto the output end of the transmission. I suspect that you don't have this brake setup, though, but I'm not positive.
