whats a good drop if i was to put 18s on a 96 explorer ? how low ? inches?

Depends on whether your truck is 4 wheel drive or not. If it is you wont want to go past 3 inches up front, at least in my opinion. Its all about your taste, If I had 18s, I would want my truck dropped alot, so as to not have alot of wheel gap, but some people wouldnt mind that, its all a matter of taste.
Check out Lowered Suspension Tech under Sport Trucks for more info



Chris