Out of all the expensive vintage guitar parts, capacitors are the least documented and easiest to mis-represent as a genuine Fender or Gibson part.

Before you pay for a high-dollar cap, do your research. A quick Google check will usually turn up a photo of your guitar's control cavity. Do you see the capacitor you're thinking about buying in there? Just because it is a red ceramic cap doesn't mean it came out of a Strat. If it reads SK .1X 50V it did. If it says anything else, you are looking at a 7 cent ceramic cap and you can buy yourself a whole bag of them at places like Surplus Sales of Nebraska.

Fender and Gibson used wax caps in the '50s right? Yes, they used Cornell-Dubilier brand caps, usually marked with C-D. Fender used teeny little brown, yellow or white caps that were developed for submarine missiles in WW2. These are heavily documented and easy to identify. They will bear one of these markings: ZYW1S5, ZSW1S5 or ZNW1P1. If it does not have one of these markings, it is not a factory install. For reasons known only to Leo and Forrest, Astron caps were used in the cheap guitars (Musicmaster, Duosonic, etc.) The pots and caps from these guitars are often sold as Tele, or Precision parts, (red or brown label Type AM Astrons or Yellow Scuba caps) but these are suitable only for restoring a Musicmaster or Duosonic guitar and besides, do you really want  to pay $350 for a set of pots when you can get the whole guitar for $100 more? Gibson used .02mF 400v Cornell-Dubilier Grey Tiger capacitors until 1956. These are also easy to identify, they are marked with GT4S2. If it doesn't say Grey Tiger and GT4S2, it was never used in a Gibson. And lastly: those old wax caps are Terrible, it's like throwing a dirty blanket over your amp! That doesn't mean you should yank the caps out of your '51 Blackguard, but if Uncle Lou did some Groovy re-wiring back in '74, you'd be better off restoring the guitar with a new cap, and that's what Luxes are for!

Bumblebee caps. If it has stripes it's a Bumblebee and it's worth a lot of money right? Maybe. The colored stripes were the old fashioned way of marking tiny electrical components with their values. Resistors have stripes because they are too small to write on. Near as I can tell, Bumblebee capacitors (made by Sprague) were manufactured with stripes for generic use by wholesalers and other companies to market as their own. These are identical in construction to the Black Beauty. A shiny black plastic tube with little circles. In the circles will be a number 2. A circle and a 2 means Sprague! From 1956 until 1960 Gibson used Red/Red/Orange/Grey/Yellow striped Bumblebees (.022mF 400vdc). These are 1.25" long by about 3/8." They switched to junk caps when they started making SGs. In '68 and '69, when they brought back the Les Paul, they used .022uF 400v Black Beauty caps. These little caps are always expensive, but just remember that Bumblebees and Black Beauties were made from the 1940s through the '70s and that cap you're looking to buy probably came out of an old television set (they're called Telecaps in the old catalogs) and may well have a different casing and markings from the Gibson installed caps. And there isn't any fairy dust in there folks, just an old piece of wax paper and tinfoil!

There are lots of exceptions to the rules. After all, these guitars were made by little companies on tiny budgets and some days they had to make do with parts borrowed from elsewhere. But if it's a dodgy cap, and you are not looking at unbroken solder connections and it is not still in the guitar, Buyer Beware, it's just an old piece of junk!

Have fun, do your research and like the man said, don't get fooled again!

Some odd caps you may find in your old guitar include: Solar "Sealdtite" in early Fender guitars and lapsteels, Sprague Orange drops in early '60s Strats, and just about anything else that would have been available at the radio shop when somebody had to run down to the corner for parts.