I'm going to be checking out that '91 NA Miata that I posted earlier this week. The owner says the mechanicals are pretty much all up to snuff. However, the passenger's window doesn't work, the back window has cracked but comes with a replacement, no radio, and it has some rust in the quarters/rockers. Also, it's a slushbox with 170k on it.

What stuff should I be looking for when checking this car out, and what things are deal-breakers that I should know about?

Thanks in advance.