C30 question

[va72longhorn]

I’m having a hard time determining whether or not the three spoke steering wheel is original to my 72 C30. I know the 1972 model medium duty trucks (C40, C50.... ) had the three spoke that the pickups carried in 67 and 68, which is the same one in my 157” wb, that started out as a cab and chassis.
I looked in the GMHeritage site and the 133” C30, for the Longhorn, is all I see listed under CE30’s. I did see where the base C&C’s for the campers are in the pickup section. I don’t see a rear axle listing on my SPID or build sheet, so am I to assume it’s a standard medium duty rear? I thought it was a HO72 with 5:13 ratio, but I’m not 100% sure. According to the chassis mounted camper section, I’m running a 5:43, since my GVW is 14,000 with a 11,000 rear.
Are the cab and chassis C30’s, longer than the 133” wb, considered medium duty trucks?
Where would I find the GM listing for specifications and options for the medium duty’s?