The RPO codes should tell you what alternator came with your truck.
Martin
Thanks for all the advice guys. Im still working on it. I had the parts store order a 130 amp, went to look at it today and its way bigger than the one in my truck..It would need a different bracket. So i know I have the right one. But still have the dropping votage prob, went to check out that 130 amp and on the way there the truck started doing the same thing and runnin like shit and the check engine light came on...so i may have two problems here......
Check your battery terminals. I'm not sure if you have the silly two Lug positive battery connections of the earlier years. But, you did mention you replaced the battery. Was it leaking from the Pos terminal? If so you may have corroded cable ends.
Martin
Just a tidbit of info...
I have 3 cs130 alternators, 2 of them have (or had) poor voltage regulation.
#1 ACdelco (dealer new/reman) 2 months old- low volt when hot. #2 Omaga (local rebuilder/reman) 2+yrs old- low volt when hot, spun pully nut, GM marked regulator. #3 ???? (local rebuilder/reman) 3+yrs old- 13.8 when hot, noisey rear bearing. USI Regulator.
#2 has a insulated rear bearing carrier, interesting. #3 has a USI (universal Scientific Industrial Co.) 71-1011HD regulator. field connections soldered. #2 & #3 have DR5162 diode assemblies.
Now, im not an expert, but I believe some replacement parts dont meet the OEM specs. Knowing rebuilders use whats given to them, they have little control over quality. If you can find a rebuilder that has the USI regulators, it may solve the low volt problem (assuming the rest of the alt is good).
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