The earlier seats should bolt right to the floor. Bolt the front bolts first as you may need to sit in the seat and using the side handle raise the seat in order to have good access to the rear bolts. The 85 seat belt latch should bolt directly to the inside of the older seat on both seats. You will also need to unbolt the sliding bar from the rear of your 85 transmission tunnel in order to get the entire seat belt latch. The 85 latches should be bolted on before installing the seats. All of this can be done with a 10mm and 13mm socket.