It would be helpful to have more info on your vehicle (year/engine/alternator, etc.). Have you tested these alternators output after installing? At minimum, start the vehicle, turn off all electrical draws (except dtrl if you have them), let it run for a minute and check voltage at battery posts when idling and again above 2500 rpms.
Assuming the alternator is producing adequate power, the next item of business is to make sure the trucks electrical system is up to *****. Even if the battery's good, cables are tight, etc. you're adding additional demand from every added light, your old worn out blower and wiper motors, etc. Now consider the fact that every connection is old and likely loses its ability to conduct current, every ground that's loose or sketchy, every splice for your lights, undersize wires and battery cables, etc. Add up all the losses and you're losing considerable current, increasing the demand even further and really taxing that junkyard alternator.
If you're going to plow with an electric pump, you'll absolutely need to upsize battery cables, redo all grounds, turn off all unnecessary lights, stereo, etc., use LED flasher/strobe if needed, and you may still not have enough amps unless you're super efficient with the plow. Biggest problem I had when I started plowing was "happy hands", meaning I was constantly adjusting the plow up/down/left/right. Every time you even nudge the plow the pump runs and it sucks BIG power. First time was in my F250 PSD with a 7.5 Western and wings. Truck went into limp mode and I thought I toasted the trans. Fortunately, I just needed to learn to be more efficient so I didn't have to play with the controls so much.
Before you buy the high output form a parts store, I would recommend checking with other plow drivers to see what they run for alternators and if they can recommend a rebuilder to have one custom built. We have one here in Grand Rapids MI called Floyd's Electric. Last alternator they built for me was for that same truck when I installed a Fisher XLS plow. Loved the plow and cut my plow times by 35-50% depending on the lot. Problem was, being an expanding plow it used even more power and was just plain fun to use. Floyd's built me a 260 amp alternator and never suffered electrical anemia again. Price, IIRC was around $230 so roughly the same price as a new 110 amp.
If you'
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ve got a reputable alt builder it could be worth your time to check it out.