I don't know jack about squarebody cruise except it uses weird parts.
Now I will say this, the most common cruise failure on OBS is the lever, or the wiring inside of it. Enough flexes back and forth between using turn signals and high beams, and the wires break internally. Also the switch just gets crudded up. I took the one in my 94 2500 and soaked it down in contact cleaner and it actually works now where it was dead before. The resume/tap up doesn't work, but at least I can turn it on and set it. One of these days I'll get around to replacing the lever.
Richard