I have a '78 Chevy bus that I installed a '94 5.9 Cummins in with an Allison automatic transmission and a Watson Transmission (Spicer over/under) behind that. Last week the Watson blew a gear. I've found out that finding parts for it is impossible, so I'm trying to find out what my options are. I have to have overdrive due to the rear end already having the the highest gears that it will hold, 588's, and I have to keep it bumped up because I drive it on the highway 95% of the time. The bus weighs about 18,000. When I originally installed the 5.9, I had a '91 5 speed Getrag behind it and it blew up within a couple of years.
I'm figuring I'm going to have to go to another transmission, so I'm wondering what kind, with overdrive, that you guys would recommend that would hold up to that much weight all the time?
Thanks

 

I would look to an Eaton 6 or 7 speed with overdrive, do a quick search here on NV5600 replacement, and you should find the epic thread that covers it, if I remember the user name right, it was Chansey.

On edit, I see this is your first post, sorry I was a bit short, here is the thread.

https://www.dieseltruckresource.com/...ht=NV5600+swap

 

Thanks