The early Prodrives are 3.5" but 1.6" tall afair.
I'm sure of that. I had the 80 MB version back in the day, connected to my A500 with Evolution controller.
The Quantum Prodrive series was 1.6", with the most common models being 40 & 80 MB.
The (later) LPS series was indeed 1" with the most common models being 52 & 105 MB.
