its 72 gmc with a 402bb. just put a new alt. of in 2 weeks ago. problem just started tonight. seems like i am getting surges in the lights and dash lights. also seems to be effecting my temp gauge but no other gauges. when i gte the surge all my lights get extreamly bright. and the temp gauge maxes out. it doesnt last a long time its kinda off and on. all the lights will get real bright for a bit never same leanth of time. and then everything goes back to normal.
i also get kind of an electrial dust burning kinda smell. might just be dust burning off the lights that just got real bright in the dash. truck seems to be running fine otherwise. just need some sugestions on where to start looking.

also truck was in a small wreck on sunday which crumpled the drivers side fender and push the bumper back like maybe an inch. (rear ended a stupid person that slammed on their breaks while i was trying to merge onto the highway) could that maybe have caused this problem?

It sounds like the voltage regulator is going bonkers, yes the accident could have caused it.

ok so i probely need to change that out then. thank you. i was at a total loss on this one.