Originally Posted by Dutchbird
As you know by now, yes there is!
Ray posted some pictures of it also, he has the same one as I have.(stamped: 1958-59-60 Thunderbird)
The trailer hitch on Alexander's Bird was marked only with 1958-1959 Thunderbird.
Before I purchased mine I placed some bids on another hitch with only 1958 Thunderbird on it.
(needless to say I didn't won that one....)
Conclusion: they were made all three years for our Squarebirds - the same shape and style - so they are inter changable. Just the stamped marking on them is different.
Sounds like they added a year in the stamping for each year, meaning itīs easy to see what model year you have.