If it is the same air bag as the other Monaco S-Series chassis the OEM air springs will be a Firestone W01-358-8897. Earlier model Monaco chassis used two different air springs, one with a 1/4" NPT port (W01-358-9376) and one with a 3/4" NPT port (W01-358-8897). Around 2000/2001 era they merely started using the 3/4 NPT (W01-358-8897) air spring and a 3/4" NPT to 1/4" NPT reducer. Most of the ones I have seen are of this design. I used Contitech (made by Continental) on our Dynasty when I replaced them, part # AS8897. We use the Contitech on all of our OTR trucks at work and they are a good quality air spring.
If you are needing to buy them and these are the part #'s that you need, I have two (2) brand new Contitech AS8897 still in the box that I would sell for what I paid for them a couple of months ago. If interested shoot me a PM and I can send you some pictures.
I also have a full description of how I replaced mine over on irv2.com. Here is a link. My air spring replacement started with post # 1265.
https://www.irv2.com/forums/f115/mods-upgrades-to-our-2003-dynasty-237276-91.html
Mike
