When we came with the idea of making our 1073 version in an API VPR series 500 module, first thing we noticed was how many compromises our competitors had to assume to fit their repros in such a small package.
We decided to make exactly zero compromises on ours. This meant making a 3u wide module capable of holding all three vintage accurate transformers, dual concentric switches , pushbuttons and same exact PCB cards. Exactly what the name says. No downsized knobs. No transformers left out. No ICs in place of discrete class A circuitry. Just what the faceplate says: a 1073 in a 500 series format.