It depends. What is the age and make of your rig?
If your rig has a Chevy engine and dates to the early 1990's or earlier, it has the GM (Chevy) P30/32 chassis.
Motorhomes in the 70's 80's and early 90's were also made on Ford and John Deere chassis, so it depends on what engine you have in there.
After the mid 90s (correct me if I'm wrong, experts) the P30/32 was dropped for the Workhorse chassis.
Life rocks when your house rolls
Senior Chief & the Cheese Queen