Just picked up a '85 Z and in the fuse box theres a few where the metal piece isnt in the box so theres nothing to lock the fuse in place. Is there any fix for this or do I have to replace the whole fuse box?

Typically, if there's no fuse spade connectors at that particular location there's no circuit present in the fuse block.

Unless the wiring has been hacked.

well the main one missing the fuse is for my heater :/