well yea theres a few things. from 77 to 79 ford had a MAJOR problem with a bad piston skirt design in the 302's and the 351w's so try to avoid those unless the engine isn't a concern. these birds seem to be prone to rusting at the bottom of the quarter panels immediatly behind the wheel. and the same on the front fenders. the bumpers, due to the factory routing of the exhaust ALWAYS have the chrome burnt off on the passenger side. And they like to rust out completely, under where you're left foot would sit when driving it. theres a seam there that was never sealed correctly. Also, check the operation of the vaccuum assist headlight covers, they ALWAYS leak, and eventually open up like its half asleep! If when running, you hear a hissing noise coming from under the dash theres also 2 other things they are prone for. if the noise is in the center of the dash its the heater controls leaking, if its on the drivers side its either the headlight switch or the vaccuum release on the E-brake (If so equipped)
hope this helps ya out!
paul