Monaco was famous for not providing actual part numbers. I had to replace all 4 front air bags this year on my 1997 Monaco Windsor to pass inspection. I did the research. The front air bags have AY-NIT14 molded into the rubber. This number does not correspond to any current part numbers. I removed the bag, and went through this 250-page
Firestone Engineering Document to match measurements and hole configurations. The Monaco front bag matches Firestone 1T12CB-1 / W01-358-5391 on page 8. The Firestone bags are expensive. I found a direct sub probably made in China that appears to be as high a quality as the firestone bags and much less expensive.
Plaza Fleet Truck Parts in St. Louis 636-219-1877 (Ron or Kevin) has a direct substitute, Automann AB1DK10A-5319. I put the first one in myself and am having an RV place do the others. Plaza will sell to the public and ship to you, but u have to pay up front.
The air fitting should also be replaced, they leak as they get older. I'm not sure what to use -- I'm letting the truck place pick the best part.
I do not recommend doing this yourself unless you are an experience mechanic with guts, with proper tools including a big air impact wrench (to remove the bottom bolt). The front tire should be removed. The top bolts are in a tight area difficult to access. You need the right size spanner wrench. You have to PB the hell out the top bolt area, scrape off all the rust to get the spanner wrench to fit snugly on the bolt, and a 28" long persuader big enough to fit over the end of the spanner wrench to get the bolts loose.
For Monaco rear air bags, you will have to remove one bag, get the measurements and hole config, and go through the above Firestone engineering doc to get the Firestone # and Automann number.
Note: These bags were probably used on all other Monacos in late 1990's and perhaps into the 2000's. If your front bag is marked AY-NIT-14, the Firestone/Automann bags will fit.