Dan,
First off, welcome to the forum. This forum, and the one run by POCA, along with Mike Dailey's
www.panteraplace.com, were my sources for all things De Tomaso prior to my purchase of 2511 in late '02.
I read the complete archives at this and the POCA forum, all of panteraplace and bought the entire collection of manuals, tech, and TSB info from the POCA store long before buying my car.
When dealing with a Pantera, you are entering a new world from what you have known confirming VIN numbers. Knowledge is your best protection to help ensure you buy a solid (BEWARE OF RUST!!), safe Pantera. First off, you have no doubt realized they do not have the 'correct' 17 digit VIN as is now common; they are too old for that, and thus a CARFAX report is worthless. They also DO NOT have a hidden VIN number, as you wrote in your post.
Buying a Pantera is a tricky procedure, if you want to do it right. Stock examples are basically not found too often, meaning each car will have its own quirks. Knowing if they are tried and true upgrades, done right and safely, or someone's back-yard waiting-for-disaster hack-job may not readily be apparent without some prior research.
Quite honestly, it seems you are moving towards purchase much too early in your learning curve. Being as you are in the LA area, you are surrounded by Pantera owners, many on this forum, that will gladly partner with you (for free, just buy lunch) to go out and inspect any car you are interested in. I benefited from several owners in this manner during my search, and have gladly returned the favor in the ensuing years. Such inspections are also possible many miles from your home should you locate a car in some other state or in northern Cal - or near me in Fresno. You can locate such friendly inspectors on this forum and on the POCA forum - all you need to do is ask.
I strongly urge you to join POCA, or at least find the closest chapter to your home and start hanging out with them at meetings and events. In my signature below are links to my favorite privately run websites and the POCA forum. There are also numerous other privately run websites - the Banzairunner website has a great section with links to all of them.
VIN numbers for Panteras are always stamped on the sheet metal top of the pedal box, in the front trunk. They are also always on a dashboard plate riveted or clipped to the dash in the driver's corner, and on most cars are also on a plate on the B-pillar.
Good luck in your search. My car has been all, and so much more, than I had dreamed of since first seeing one in 1972.
But it is the people that come with the car that is the real surprise when you join the De Tomaso Family.
Welcome!
Larry