My bad... I thought you had a C30/R30 square-body dually. You found one of the oddballs. During the 88-91 transition - especially 88-89 - GM produced a low GVWR 1-ton in the 'new' body style; essentially a 3/4-ton. Anything you're short on (like hydroboost) can be beefed up with parts from a 1-ton truck built a few years later.
The 70-3HD also uses unique ring & pinion sets. Its another 88-91 oddball... the 14boltFF got used exclusively from 92+ in the GMT400 trucks.
Looks like you've done a lot of work already. You're probably ahead condition-wise on most 2ndgen Dodges. IMO, the build quality is similar. (They even share some brake parts!) The difference is mainly having IFS 4x4 vs the Dodge solid-axle.
I recommend you keep on researching conversions. This thread is specific to the 73-87(91) square-body chevs.
Be sure to add GMT400 to your search terms. Maybe check out some of these threads and forums:
https://www.gmt400.com/threads/1996-suburban-cummins-swap.15670/
https://www.dieselplace.com/forum/6...93-98-chevy-cummins-conversion-pics-here.html
https://www.cumminsforum.com/forum/...5-chevy-ccsb-12-valve-cummins-conversion.html
