César Carrillo Díaz (July 13, 1951 – April 26, 2002) developed adjacent / convergent practices to Jose in the same era of hot-rodded Marshall building, ultimately becoming Stevie Ray Vaughan's amp tech (and a sought-after modder in his own right). Builder-bio specifics: Díaz was Puerto-Rican-born and ran his amp shop out of East Stroudsburg, Pennsylvania — so the "trained alongside Jose in LA" framing overstates a personal relationship. The shared aesthetic (pre-tone-stack MV, restraint with diodes) is real, but Díaz's path traces through his own session-tech career working with Johnny Nash, Frijid Pink, Bob Dylan, Stevie Ray Vaughan, Eric Clapton, Keith Richards, and Neil Young — a parallel East-Coast / blues-rock branch of the family tree rather than direct lineage from Jose's LA scene.
The Jose → Díaz family-resemblance is part of why "Texas blues" Marshall mods and "LA rock" Marshall mods often share the same DNA: pre-tone-stack master, cathode-bypass switching, NFB reduction, and (importantly) restraint in the diode-clipper voltage choice. Díaz's mods tend to favor higher zener voltages or even no diodes at all — the player's right hand provides the dynamics.