Interesting, I also found the diode in my 84 module is rated at 60v reverse current, and the one that blew up in the 86 module is rated 600v...time to swap that bit then experiment some more. Yes, and the C3 (orange) and C4 dimmers (black , early C4) are interchangeable. The circtuit board inside is almost identical, the case is different. The only thing is that onn the c4 the tab for the connector is on the other side so when using a c3 one in C4 or vise versa you have to push the conenctor in w/ the tab on the wrong side. For more information you can refer this link.