So everyone Im looking into changing brakes on my 89 Gta I was told that the 4 th gen are a direct bolt on with no mods I'm wondering what I need to do the swap

Whoever told you that ... if they were talking about the fronts (the ones that matter) ... you don't need to be listening to, because they ... have a lack of alignment with reality.

The calipers are COMPLETELY different. To mount them, you need a bracket, and a caliper "abutment", which is a sort of cage-like thing. You have to modify your spindles to be able to add the bracket. You have to make hubs by turning down a 3rd gen one to get rid of the rotor.

Other than that, it's a bolt-on.

Go here for some kind of a clue. www.bigbrakeupgrade.com Not that you necessarily do, or don't, want to buy from them; but the pictures will show what's necessary.

Nowhere near bolt on lol.

People were telling me that u get the Knuckle, hub, caliper, an the brake pad retainer an it will have everything on it to make it work then bolt it on directly from that

nope. two completly diff designs.. It can be done but as said above its not a "bolt on" ..

Only way it would be a bolt-on, would be if you bought the complete kit, like the one from bigbrakeupgrade.com.