SHaugen,
I have 2 of the largest lightforce lights and 4 of PIAA's largest lights plus HID headlights in the front end and on the front of my truck and the old alt(125 amps is what they are rated at) could eaisly handle it. The lights draw about 4. 8 amps apiece. But as you might still want to upgrade, go to "Mean Green" (on the web) in PA and they sell a direct drop in 200 amp alt. That is what I did instead of putting new bearings in my old alt. If you exceed about 2 thirds of your output consistantly, you will shorten the life of your alt. If you under tax your alt by a bunch, you shorten the life of your alt. Figure your entire electrical load, (heater on high, lights, wipers, windows etc and make sure it doesn't exceed about 65%. Then you will be ok. Hope this helps.
WD
P. S. I would attach a picture of the truck if I knew how to.
WD