I recently bought a '65 F250 and in the glove box was a NOS box with a big ceramic resister in it. Part number is: C3TZ-12A046-A

I can't find anything on the firewall where it might go. I found the same part number listed by a guy on Ebay claiming it's for '63 '64 427 HiPo cars. He's an ex-Ford parts guy and when I asked about application to trucks he claimed he didn't know.
What's it for anyway and is it a cross application if so, for what?

 

I dunno, but this guy is awfully proud of his, wants $275 for one. Looks like it's used as a ballast for certain types of ignition systems.

http://m.ebay.com/itm/NOS-1963-1964-...-/290867900513

 

Left pic (from 1964/72 truck catalog): Scroll down to 12A046

C3TZ-12A046-C = Used with trans(istor) ignition system on the following 1964/72 (500 and larger series trucks, as these engines were not installed in F100/350's).

Right pic (from 1965/72 Ford car parts catalog): Scroll down to 12A046 / A = Galaxie/LTD; S = Thunderbird.

 

Wow! Is all I can say Bill. You're the best. So it is for the F500 series OR/and the Hi-Po engine cars as well. I'm not as "proud" of mine as he is of his though. Thanks so very much.