Originally Posted by 4eyedfoxdriver
Frame rails, floor pans, and torque boxes are all good things to inspect.
As long as its not from the northeast the rust shouldnt be that bad. It never hurts to check regardless so in addition to those 3 listed by 4eyedfox i would also check the rockers, especially if its a GT as the retainers behind the ground effects trap water which can find its way past the rivets and inside the rocker. There are retainers on the fenders and the 1/4s. The pinch welds next to the floorpan should be inspected as some people simply have no clue where to put the jack and fubar everything. Also check the fender mounts at the rocker. I have had to cut bolts off to remove the fender it was so rusted. The 1/4s can be another trouble spot. The rear can rust away just ahead of the bumper cover. The wheelwells themselves are an often overlooked area. I have seen some shotty spotwelds at the lip, which allows water to pass. It will collect at the bottom behind the 1/4 next to the rear seat. That can be a hard spot to get to btw with the inner structure back there. This goes for any bodystyle and any year from 79-93.
If its a vert you have a couple more places to check. Look behind the backseat for rust or leaking pumps. If the top mechanism is tweaked the top wont seal and water can find its way in. There are drains which should be occassionally cleaned out. If its a t-top or sun/moon roof, do the same. There are drains from the roof that pass thru the A-pillars IIRC. There may be drains in the B-pillars, i dont remember.
The northeast loves salt. The southern states still have rain which can do the same, so check everything. Should you need them, you can buy replacement floorpans, front frame rail kits (tho not exact for 86/87-93 if youre a stickler for details), outer rockers (which need a lot of work to fit and look right...they are horrible imo), inner rockers, rear framerails, and entire trunk/hatch floors that include the section under the back seat.
Most of the other stuff will be weatherstripping and possibly some electrical bits like power windows, and door lock actuators. Vacuum leaks can be common on old or neglected Foxes. Try to stay away from hack jobs tho. They can be a major PITA.
The youngest Fox is only 22yrs old and even they are beginning to wear out. Dont let limited knowledge turn you away. We all had to start somewhere. Got a problem, we will help. Thats what we are here for. As for your budget...that depends on what the car needs to remain safe and reliable. That should be your #1
Tools. Dont forget the tools. Basic handtools, service manuals and fuel injection manuals always come in handy. And a code reader. The EQUUS 3145 code reader is perfect.