Hello everyone..I love my J.D. sled but I can't keep a headlight in it..The factory bulb (AM52959) seems to be a GE-4492, now obsolete. This is a 60W/60W 5.5" (par46) sealed beam. I am using the common H5006 automotive bulb as a replacement. They last less than 2 minutes. Tail light works fine, on all the time, never blows out. The system is 12 VAC, (yes, AC) with a regulator which I checked and seems to be working fine, measured voltage is 12.5 AC, steady as a rock..So why is the headlight burning out so fast? I figure it MUST be vibration, but vibration level seems to be moderate and normal..Or the automotive bulb somehow does not like the AC current. Can someone tell me why the 4492 ($25 each) is so special or am I overlooking something?