WBCCI Numbers question?

[tiniree]

Hi Everyone -

Have posted a couple questions here in the hope that my husband and I will become the proud parents of a 1978 25ft Tradewind International this weekend (if all systems check out). I was searching the posts to find out about the numbers located above the end window and have discovered that they are old WBCCI numbers. The trailer we are looking at had them at one time as we can see the imprint of the first two numbers 1 & 3.

Was wondering for those of you who are restoring your AS, do you also put the numbers back on? Are these numbers given to the trailer "for life" or were they a number given to use while an annual fee was paid by the owner?

Thanks in advance for giving us "newbies" a way to see our dream of becoming an Airstream "parent" a reality.