1952 Hornets had 6volt systems.

I know. I'm coverting to a 12 volt system. I pulled out the 6 volt system. Im looking for a new harness to buy for the new 12 volt

Definition: The wiring harness is the whole wiring of the car, or the wiring bundle of a specific area, such as "engine compartment wiring harness". On these old cars, there are not separate harnesses, with a connector at the firewall or such; there are pretty much individual wires going to components.

Okay, so are you looking for the wiring to adapt an alternator?

Since the 6-volt wires are all of a heavier gauge than 12-volt wires, I would assume that the existing 6-volt harness could easily support a 12-volt system. (If the harness is in good condition, of course.0 The only difference between the two harnesses would be whatever extra circuits must be wired in for whatever supplemental electrical components are required to convert from 6 to 12. But I would assume the number of these components would be minimal.

A new basic harness is expensive (YnZ's charges $1200 for a '48-49) so if your existing harness is in good condition you might want to opt to retain it for use on the new 12-volt system, rather than spend $1200 on a new harness with lighter gauge wires for the 12-volt system.. You can then simply add the few wires necessary for any supplemental components, yourself.

The 6V wiring is more than adequate for 12 volts, but you may end up replacing parts of it due to age and deterioration of the old insulation. I wouldn’t replace the whole loom, just piece by piece as required. And unscrew, clean, and put something corrosion inhibiting on all the connections.

I buy 12 volt universal harness from Kwik-Wire co. Made in USA a little more expensive than the cheap Chinese harness but better made. They come with a nice fuse panel , all the wires are well marked, they have a built in kill switch on the fuse panel, wire for electric fuel pump, and wire for electric fan, and A/C wire. I have one of their harness in my 46 Hudson pickup, and in my 40 Huppmobile. When keeping original 6 Volts I use YNZ’s, or Rhode Island wiring harness. All three companies have web sites.

I have taken a harness apart and using automotive grade wire, copied the wire size and color, and built my own harness.
I also solder every connection/connector. No crimp fittings.
https://www.delcity.net/store/Wire-&-Cable/?mkwid=s&crid=437924053097&mp_kw=automotive%20grade%20wire&mp_mt=e&gclid=CjwKCAjwlID8BRAFEiwAnUoK1b5Cnw3Kcq43VTXmuZC-hQjLn87rblwmK2mHiQPkV56cyiYOpcHEvhoCMlkQAvD_BwE

I used to be hard core "solder only". Then I went to some connections crimped and soldered. As I've reached retirement age, I'm thinking that plain crimps, well compressed, will outlast me. 😉

The thing is to get a real good crimping tool one that really pushes the terminal into a U-shape so the wire is properly fastened therein, and finish off with h eat shrink. The cheap-junk accessory store crimping tolls just don't work.

Ron Francis makes what they call a 6V replacement harness. As jon indicated all 14 Ga wire, 12 circuits, 3 relays built in with sub harnesses for typical loads like the lights.All wires labeled.
Costs about $550 as i recall. Part No. WR-54

http://www.ronfrancis.com/products.asp?dept=21
Link for 6v Ron Francis Wiring.

I misremembered, it's only $309.