I recently purchased a 98 dodge ram 1500, standard transmission, 5.2L 318, 4 x 4. I've already done some work on the truck... Most everything to do with the cooling system. After replacing the water pump I had a friend tighten the negative battery cable. Since then I can't keep the battery voltage up. I've changed the batter, battery cable clamps, and alternator. The problem remains the same the voltage is wacky... Apparently a technical term as it is the parts guys word not mine. With some research I learned there are 2 different alternators for the 5.2L...90 volts and 136volts. In several places it says magnum on the engine. How do I know which alternator I need? Or if that is in fact my problem?