Good info and awesome truck! My 833 is a MM7 steel body with the flat Hurst shifter in my 85 K10. Midwest Transmissions rebuilt mine and I just recently got a shifter from Shifter Doc.com. I plan to rebuild my wore out shifter and save it or sell it.
I'll add a little here, parts are available for the transmission, the shifter is the hen's tooth. The Hurst Comp Plus shifter for the Mopar NP833 will not work on the Chevy since it's an overdrive unit. I found a rebuilt unit at Shifter Doc.com and snapped it up as it was the only one I had seen...