it all depends on the electrical load you are placing on the stock system !!!!! I myself installed a g3 130 amp. in my 73 maverick 4speed because I have two electric fans,AC, msd 6al and a Hi-power stereo system in the works. the big plus is less wires and the life time replacement, but for a nice replacement/factory look I would use a solid state regulator and a quality rebuild the original alternator or buy a hi-power replament and keep the original. on my 63 fairlane I put a 63amp alt. with a new regulator and gave away the OEM generator and brackets...