does my truck have a socket or hei distributor cap? what is the difference? also, what is tfi? im looking around for a set of spark plug wires and i keep seeing alot of "universal" sets that you can cut to size, but they are usually sold either for hei or socket caps. i am not new to my truck, but i have become suddenly confused. truck in sig.

 

Socket is the old style(plug the wire in the hole), HEI is the cap with the brass contact sticking up from the top of the cap. Most all the newer stuff is HEI style. It's simple to check by pulling one wire off.