I don't know where one would find a list of all the allpro teams, but a quick hit on google turned up this quote from Gaechter's hometown paper
<<Gaechter excelled in the NFL, and he was an All-Pro strong safety in 1965. "It was a nice honor … we had one of the best defenses in the league, which helped me a lot," he said. >>
Lots of credentials grow in the telling of course.