1984 or 1985 -- Does it matter?
You bet, it matters -- at the parts store, anyway.
Evidently Airstream would bulk purchase a number of bare chassis, as an example, in my case, 1986 model chassis'.
When they got around to completing them, they may sell them as the following year model. Again, in my case, as a 1987 model.
To the consumer, it really doesn't matter, 'cause you get what you buy. I suspect they made slight changes over the entire course of the model run. But..........
At the parts store, make sure you give them the year of the chassis model.
In my case (AS 1987 model vs Chevy 1986 chassis) there was a huge difference in the engine components (86 chassis vs 87 chassis). ('86 Carburetor vs '87 fuel injection.) Many of the components are different, SMOG control, fuel pump, belts, etc.
When attempting to replace an engine part, I have found it best to have the part in hand when I walk into the parts store, it may well save another round trip to pick up the proper part, and a lot of frustration attempting to get the wrong part to fit.
"Suck it up, spend the bucks, do it right the first time."
WBCCI # 1113
Trailer '78 31' Sovereign
Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
Texas Airstream Harbor, Inc.