Hello, Paul,

Welcome to Stovebolt.com

EL-170C is a 50-52 Chevrolet Truck alternator wiring harness. Jim Carter still sells it.
It has plastic-coated wires (unlike the original cloth-braided wires).

How many wires on your alternator? 1, 2, and 3 wire alternator might have be added/used.

That harness did-not/does-not come with a wiring diagram (it might come with a list of circuit names and associated wire-colors).

Here is a link to a copy of the 1951 wiring diagram that has wire colors (Jim Carter wire colors should match).

Do you have a 1951 Chevrolet Truck Shop Manual? It also has a wiring diagram in it. But, the diagram on-line is unreadable.