You can make one if you have a high-quality tape deck, Just record
some of the higher frequencies in the range of 4K and above, and use
that to align your subject tape heads. Should be no problem if you
have a audio generator and a good tape deck to make the master
alignment tape.

This reminds me of the joke about the town that set its public clock when
the local fort fired its canon at noon. The fort, of course, fired the canon
when the clock struck 12:00.