Note that the 60 AMP alternator have a little more going on inside with mechanical and electrical issues. Brushes will wear, weak springs, dirty slip rings can lead to wonky (technical term) output. Where as the 200 amp units are of a brushless design eliminating these wear items. Nice to have but not a big deal, BUT it is a BIG DEAL IMO.
Both can have wonky output do to a zapped regulator, diodes, winding, soldered connections, etc
60 amp trucks are wired thru the PCB and its body connector / wiring harness. Good idea to check this plug and contacts for poor connections, looking for bent, burnt, loose, corroded, poor fit-up or just plan nasty as they are both male and female parts to this poor design for a charging system. Just more crap to go wrong at the wrong time... not to mention FET / relay, control circuits in the PCB.
Once it is determined 60 amp er is at fault, most of the action can be rebuilt with the CORRECT back plate holding the brush and regulator assembly.
Don't forget to disconnect batteries before starting ANY work and double check all connection. There's a couple that are CLOSE together under the little cover. (cuss area). Clean or upgrade grounds system.
Good luck and charge on, CAMO
