High volts

I was just looking on year one to see if they had a plug and play engine harness to fit a 74' slanty swinger but nothing listed. Couldn't find one anywhere else either. Figured if I could get all new ready to go harness it would be better than paying someone one to search, find and replace any of my problem areas.

Just back from the local electrical guru, (he's a 1 man shop been doin nothin but auto elect for 30 yrs) Told me that the culprit is prob the gauge itself as all the volts or amps (whatever the hell) go to it from the alt?(think he said), (Can you tell electrical is not my bag) So wondering now is a new gauge avail somewhere or should I just put in an aftermarket if that's the problem. I already replaced the vr with one from advance and had alt checked on and off car. He told me to get another vr and not chinese junk from chain stores.... Is there a way to test a vr off the car? ... txstang, sorry I really don't intend to hijack your thread, havin the same prob and thought this might be better than starting another one. If I'm wrong PLEASE set me straight, Thanks