Every Fox I've owned has had floorboard cracks - some worse than others. If you have a welder that you can run low power and some rudimentary skill, you can "repair" the cracks at least enough that they won't allow water in the car, creating a foothold for rust. Take your seats and carpet out if you have the inclination (reduces fire hazard and allows access). You will probably scare yourself with how many cracks are there. The only areas with any real strength in your floorboards are the anchor points for the seats and the seatbelts. If you ever do pull your carpet up and inspect the damage, you will almost certainly want to add reinforcement in the form of subframe connectors and seat anchor backing - another job for the welder. If you take it somewhere, you run the risk of them burning your carpet, seats, etc. and the potential for some serious overcharging. If you find a decent place to do the work for you, expect to pay a couple of hundred bucks for the repairs (another reason to consider purchasing a welder if you don't have one, or better yet, borrow it).