defrost tubes very nice originals

Atleast 3 different pairs were produced. I know 67 thru 72 are different from 73 up.
Then 67 thru 72 with a/c is different from without a/c.
As far as I know 73 and later are the same with or without a/c.
For a 67 thru 72 without a/c , one tube is the same diameter on both ends where the other tube is larger on only 1 end.
Hope this helps