Smithereens.
You are correct.Trower tuned down a whole step.

AC/DC is somewhere in between a 1/2 step down and standard....like Van Halen on the first album.
I was playing along to Highway to Hell the other day and it's not quite a 1/2 step down.
They most likely did the "give me an E" tuning system in the studio.
There were a ton of bands, particularly in the 60s and early 70s, whose recorded output was always a couple of cents off in one direction or the other, not even a half step. It was crazy-making trying to learn anything.