Do Not remove the slotted screws!!
Might be the case on a post 93 car, but
NOT the case on a 1972 4/4 with steel wheels. As the OPs car is an 86, highly likely the ironmongery is the same, although I've not closely examined a wire wheel car of the same era.
There are definitely NOT four bolts holding the drum on, and if you want to take the axle apart to get at the brakes, you are in for a major and quite unnecessary battle.
OP post a photo of your car, with the wheel off showing the drum in place. There are a few confused folk here.