Not sure which alternator i have on my 2001 f150. How do you figure out which one you have before going to parts house ?

 

Umm are you going to a salvage yard to find a replacement? Otherwise just tell them ( the parts store ) the year and engine size and they go get it for you.....

 

if he has the 5.4 they are two sizes in amps the best thing to do is find a shop around you that will rebuild it i had mine rebuilt and it wasnt but like 75 dollars that included him taking it off and putting it back on a heck of alot cheaper than a new one from advance and alot better imo