b26i with dual 12's and 350w amp

the big 3 helps with dimming issues as well. depending on the power you are running. as mentioned above, a higher output alt would be a good idea.

Col sanders is right. Caps and another battery with a isolator is a band aid. I used a cap with good luck, (also worked at car adusio store and got it for cost and was to cheap to get alternator) but it will only get you so far. ALternator is the right way to go in the long run. But having a cap or dual battery set up as a back up doesn't hurt either.

what size alternator should I look for though? like a 120a?

Depends on what else are you going to run. Stereo, compressors, any accessories that you may use need to be considered. There is a thread on using a Ford 150 amp. That is plenty stout.

I've got a ford aerostar 130amp alt in mine. I'll upgrade to a bigger battery eventually.

I also run LED strobe lights for the fire department but today's lights require a lot less amperage than the old strobes lol

whats the best year to use and the best way to mount a ford alternator?