Installed a GM 10si alternator in my truck. its an 85 SR5, 22re. i was out wheeling last night, had my stereo going and my heater on, and noticed my lights were getting brighter, and then darker, kind of flickering. i have a stereo system in it. 350 watt amp with a 10" kicker. when i got back to pavement and began to accelerate the truck started bucking like crazy and my dash lights went almost dark and my stereo turned off and back on. curious as to thwy this is happening. with heater and headlights on the truck stays around 13.8 volts at the battery. when i rev it it comes up to around 13.9-14.0 volts.

 

Sounds like you have a poor connection some place.

It might be as simple as a bad ground.Might be a broken wire

A short someplace not causing circuit protection to open depending on how the truck flexes

 

grounds are a hell of a thing. lol failed to ground the battery to the body. all is fixed now. haha and went through and cleaned all other grounds.