Im going have a go at making some wiring harnesses for lights, etc. and I was wondering what thickness I should be looking at.

get a factory wiring schematic//they have all the different gauges of wire listed on them// schematics i believe are listed in FAQ section or if you buy a factory service manual they have it in there plus a whole lot more for about $25

Are you referring to the Haynes type manuals? I bought one for the '70 and the donor Caprice and have thumbed thru them. I noticed the wiring diagrams but no information to indicate wire size. I will look again tonight. Thanks.

These diagrams have the guage and color.

http://www.geocities.com/chevroletc1070/wiringdias.html

Here's a great site for you.
http://www.6066gmcguy.org/wire-tips.htm

a factory service manual is the manual printed by the manufacturer for that secific year and model car/truck when it came out of the factory

This is one of the many things i love about this site...you can ask any question no matter how basic and get a wealth of info instead of ridicule! :) I really appreciate the help!

I have a service manual for my '73. It's awsome. Shows how to rebuild altanator, AC compressor and transmission etc...