Jackson Electric Guitar
One word of advice: If you are going to buy a San Dimas Charvel or Jackson, do your homework. The strat headstock Charvel is one of the most forged guitars of all time. It's also one of the most likely to have been messed with / modified. Finding a legitimate unmodified guitar with a neckplate that matches the logbook is truly rare. Also, with so little information available on these guitars, many end up being innocently (or otherwise) misrepresented. I would highly advise against buying a bolt-on San Dimas guitar without first verifying the serial number with the Jackson Custom Shop. This can be done on the Jacksonguitars.com website under the "Serial Number History Chart" link.
That being said, here is some information to help identify / authenticate San Dimas Charvels and Jacksons Guitars.
Jackson Guitar Neck
From skunk stripes to sharkfins, more than you wanted to know about necks
Headstocks
Strat vs. Jackson style, here's a rundown
Jackson Guitar Bridges
Are you an oval or keyhole slot man?
Jackson Guitar Neckplates
No, your Fort Worth Charvel wasn't made in the USA (really)
Jackson Guitar Parts
Normal people don't get this excited over brass
Japanese Charvels
Here are some alternatives to thrashing with your San Dimas