I replaced mine a few years ago. The part number is stamped on the wheels. I installed 2 hole buds. Accuride 32068 maybe now replaced with 29388. These wheels are still being used by the Freightliner MT-45. Have not checked to see if aluminum wheels available, but stainless liners are.
I couldn't find any 19.5 wheels off the shelf to work with 245R7019.5 for the rear. I always wanted to get back to the same diameter as the original 8R19.5 tires. All wheels that were either steel or aluminum were 6 inch width and offset would not allow 245 only 225. 245 tires really need 7 or 7 1/2 inch wide rim.
I got a set of steel wheels 2 hole made by wheelsnowinc.com and were very well made. For the rear, the increase in unsprung weight would not be an issue.