What size wire in a CJ-3a wiring harness?

Just don't use a smaller gauge wire then what your trying to re-wire if that's what your try to do? Some wires in any harness are different if you got the wire stripping/ cutting crimping tool you can take the wire your looking for and run it into the crimp slot of the tool and whichever one it sits the best in is the best gauge wire your looking for.