Thank you for your follow-up to my posting back on June 2013.
I am so glad that you were kind enough to reply about what you found on your 2001 Monaco Executive, in that all 10 air bags were the same as the front part number I noted in my OP, ie Firestone W01-358-9376 (Monaco 8619), which use a 1/4 NPT threaded port for the air line fitting.
From physically inspecting the air bags on my 2001 Dynasty (no-tag), it appears that all 8 (front & rear) are the same configuration or style air bag (Firestone 1T-Reversible Sleeve) and all use the 1/4 NPT threaded hole for the air line fitting. After reviewing the Engineering Drawings of both styles of air bags, the only difference that I could see between the Front and Rear air bag that Monaco suggested were on my coach, was that the rear used 3/4 NPT threaded ports, but it appears that all my air bags have the 1/4 NPT ports.
This now gives me more confidence to order all 8 air bags having the same part no as the front as noted above.
I was interested to hear of that your air bags were badly weathered after about 50,000 miles, which is likely similar to what I am experiencing on my Dynasty that has just over 52,000 miles. I have attached a couple of the photos that I took of my air bags and what they looked like when I took photos of them in late 2013.
As a result of my examination of the condition of my air bags, I contacted Firestone Tech Support and they agreed that it is likely not an urgent requirement to change them, but strongly suggested that I start to make plans to replace them in the near future. They indicated that there is a thick inner liner inside the air bags that provides extended service life, BUT that when the outer layer of rubber is extensively weather checked that this now exposes the inner liner to weathering that will shorten their service life.
Thank you for sharing what you had to do to access the nuts on the top plate of the air bag, as this gives me some additional ideas as to how I handle the difficult access issue.
Hope you have wonderful summer and happy RV'g.