Welcome to the forums and to Argosy ownership.
Looks like a very nice trailer. I know you will enjoy it as much as the rest of us.
I think your 74 might be a 75. I only say this because my 74 does not have the vista windows. However I may be wrong if that was a change in the middle of a model year. The vin number tells the year. This thread is a list of Argosy vins. Please add yours.
Looking at your pics, someone changed the original tail light. But that's not a bad thing. The original plastic housing cracks after 40 years. I was able to fix mine but it already has a few hairline cracks in it. In hindsight I should have changed to something like yours.
I'm sure you figured out already, this forum is a wealth of info. Never hesitate to ask anything.
And again welcome. Nice to see more Argosy and Airstream owners.