Where to find an engine wire harness?

#14 wire is plenty big for the senders. They dont draw hardly any current and proper wire size for fusing correctly is not a issue here where a direct short will cause no harm to the wire(but might damage the gauge). I perfer #14 because the 16-14 awg heatshrink terminals fit well and are not huge. #12 wire uses the next larger size terminals. Also, make sure there is a breaker or fuse on the + feed line from the engine to the dash!!!

Okay, so I'll use #8 for the feed/gnd wires. What about the senders etc? Is #14 good enough?

My brother runs a production line at a company that makes wire harnesses for helicopters, airplanes, etc. He's going to make me a new wire harness, and use their wire printer to print whatever I want on the wires. I'm going to have him label each wire for me.

I'm pretty sure I still have the old style alternator, and I'll probably upgrade before next summer. But the wire harness I need is from the 8 wire plug to the dash, not from the engine to the 8 wire plug. Now that I think of it, though, maybe I'll have my brother make the other end as well. Or maybe I'll buy it from DIM.

I've searched SkiDIM, but can't find one that would work on my 74 Mustang.

You'll more than likly have to fab your own. If there's a Heavy Truck (Mack, Peterbilt etc..) Dealer in your town, you can buy a 8 in one trailer wire. It's sold by the foot and make your own connectors (ends) It's very heavy duty, I made the wiring harness for my '65 out of it.