I am still running the original Armstrong in my 72.
It has survived very heavy use over the last two summers, which is about 2/3 of the five year lifespan of a new unit.....
It still cools great.
It is riveted down big time.
When I was building my trailer I was set on replacing my old Armstrong, then I started reading up on air conditioners on this forum. I noticed two things;
A. How long Armstrong's usually last.
B. How long many modern units do not last.
I kept my Armstrong, and I am glad I did.
All I did was clean the unit up, clear it out, and replace the top cover.
1/2 Ton 4WD Truck, 72 Sovereign