My husband left me with a '73 Mustang convertible that I have no interest in keeping. Where would be the best place to sell such a beastie?
craigslist
Do you have any pictures? Does it need any work? Perhaps you can sell it to someone here for cheap. Ahem 
Real car people will be in to offer you good advice, but until then here is a thought: Depending on what kind of shape it is in, you might try going to one of the car shows and hanging out and talking to people. For reasons I don’t get, both Carlisle and York PA have car shows every year and it seems possible that they have them close to where you live too. People from all over come to show off their cars, look at cars, trade cars, talk about cars, etc.
It really depends on what shape it is in. There are Autotrader mags for that era of cars to help you price it.
Hemmings is another good place to go to get feel for the market:
http://www.hemmings.com/classifieds/carsforsale/ford/mustang/?year=1973
You should also check with the local Mustang shop (classic car shop). They can help out as well, and they know who the local collectors are.
Craigslist hasn’t worked. Unfortunately, there’s nothing local to me and I know nothing about cars so me going to a show and talking it up isn’t likely to help.
My sister said she’d sell it for me, but I’m feeling a bit guilty that it’s sitting in her garage.
The shape it’s in determines where to sell it?
Not many, though here’s a shot with my husband in it.
Yes, it needs lots of work.
And, regrettably, I can’t do that. Sorry. 
It’s a little hard for us to guess when we don’t know what part of the world you live in. And yes, the shape it’s in determines where it can be sold. Are we talking a parts car, or muscle car auction?
Don’t write off the SDMB - for example, my first car was a '73 coupe. This weekend, my neighbor the collector was washing a '71 or '72 Mach 1, and although I’m really really not in the market this year, it did get my imagination stirring. That someone else on the board likes the sheer size of a '73 isn’t beyond the realm of possibility.
Do you know where he took it to show it off or have work done? If the car’s in decent shape, there may be someone there who’s admired it in the past.
I’m in Ohio. Sorry, I’m used to that showing up under my name.
It needs a lot of body work, though he put on a new top and had the carpet and upholstery redone and my BIL rebuilt the engine right before he (BIL) parked it in my garage. (Later, BIL moved out of state and gave Steve the car.)
I live in a tiny town and there are very few “classic car” resources available locally. Craigslist has gotten zero response. The economy here is devastated, etc.
My sister knows some car dealers who work with classic cars. They gave her a place to start, price-wise, but both told her it would take a while in this market. I guess they weren’t kidding!
And that’s pretty much the extent of my knowledge of the car. Oh, it’s got a 302. *Now *that’s the extent of my knowledge of the car. 
I’d try Mustang Club of Ohio; they have a Classifieds section, and I’ll bet the members would be happy to help you out.
There is also a Western Ohio Sports Car Club of America; a TriState Mustang Club, a FoMoCo Collectors of Northern Ohio Inc., etc. There is a list of Ohio car clubs here.
Good luck jsgoddess. 
I’d gladly take it off your hands if you really want it out of the way…just help me pay to transport it to New Orleans.
Seriously though, there are lots of Mustang resources on the web. Check out MustangForums.com.
If you know nothing about cars, find someone you trust who does so that someone (like me) doesn’t try to convince you that it’s a rust bucket that’s only got scrap value. Old Mustangs can be worth a small fortune depending on the condition.
They all had serious rust problems and some are unsalvageable if they’ve been exposed to the elements for 30 years. But even in that case, there are still parts that may be worth money.
There are a few companies out there that make brand new parts for old Mustangs. But even with those companies around, there are still parts that can’t be bought new and if you have those parts intact, they can be worth a good bit of money.
That year of Mustang is notorious for emitting toxic fumes. It was painted with paint containing lead, mercury and polonium. The unique structure of the undercarriage also makes an ideal home for black widow spiders and poisonous fire-ants. Keeping the vehicle around is a health hazard. Send it to me; I will dispose of it properly for a small fee.
That’s where I go to dream.
Have you considered Ebay? People from all over the country would see it for sale, a much bigger market than anything regional like the midwest. I sold a beat up 76 Gremlin on Ebay, to a guy a few hundred miles away.
Thanks, all, for the suggestions and well-wishes. I’ll take a look at every idea.
Wish me luck!