Starter

Get a multimeter (free w/ coupon at Harbor Freight). Measure from the starter's case to its big stud while trying to crank. If <8 V, don't blame the starter. Test more to find the voltage drop, which could be from the case to BATT- (ground return). If >8 V, the starter is at fault, assuming the engine turns over by hand (tug on fan belt). Often the problem is that the copper contacts are pitted. One is the flat spot on the other side of the big stud. You can take it apart to see. You might put a washer behind it to get some more year's life. But, if you hit the junkyard on half-off day, you can probably find a newish one from a V-8 Magnum truck (until ~2001) for $10, and don't forget the RAM Vans.