same here i bought the car for my wife for her x mas gift she bout fell over last wedsday when she got home and opened the garage im replacing everything for a peice of mind and the previous owners have stuff wired up funky lol so im slowly getting it all replaced and thats the last electric part under the hood to replace

 

Do you have to replace it? What is not working? It does not look like a relay to me.

 

Found another present for you to get the wife! http://www.americanautowire.com/64-66mustang.html

 

OMG. OK, that's a General Motors horn relay, WTF it's doing is anyone's guess, and you also have a General Motors ignition ballast resistor, also strange, since the under-dash harness has one built in (unless that's hacked as bad as your engine compartment wiring, too) and I have no idea what that little electronic box is, maybe an alarm system?

First thing I'd do is break out the wire-cutters, and clean up the engine compartment. There should be almost no wiring over there. Use the factory wiring, it's very, very good.

 

the lil square box is the electric fan relay and yes we are gonna buy a new wire harness and have arizona hotrods install it, the factory harness is cut up with a splice here a splice there

 

i like that kit i may run up to rods for mods since they r a dealer its not to far from me

 

Good luck with the new Mustang. A guy on e-bay has the kit for 579.99 with free shipping and he's in Vegas: American Autowire

 

thanks wife is wanting it painted ect i want to add after market led tail lights ect but still keep it looking factory (sleeper) in the works is gonna be a stroker motor with dart iron eagle heads or world heads im wanting to keep the compression around 11.0-1 love the t5 trans now just gotta get the funds to do everything

 

car goes in in march for the wire harness kit to be installed

 

11 to 1 iron heads? Where are you going to fuel up, the race track?