Welcome! I see this is your first post.
From this website>
http://vintageairstream.com/frequent...erial-numbers/
Q: How do I decipher the serial number on my trailer to determine the year made?
A: Serial numbers weren’t standardized until the mid 1960’s. I’ve captured these early formats in the info under each model type in the photo archive section.
For late model trailers:
1969 to 1980
Digit 1 = I – International; L – Land Yacht; E – Excella
Digit 2&3 = Length
Digit 4 =
A – Center bath twin beds
B – Center bath double bed
D – Rear Bath double bed
T – Rear bath twin
Digit 5 = Model year
Digit 6 =
J – Jackson Center, OH
S – Cerritos, CA
V – Versailles, OH (Argosy)
Digit 7-10 = Sequential serial number -3 Digits 1966-1969, 4 digits 1970+
ps: the 1970 models could have been built in the late summer and/or fall of 1969, just like the vehicles sold these days.