If you are swapping a 92 engine into a 99 the upper intake is different. The 92 doesn't have provisions for the intake air temp sensor and boost sensor. The 92 timing cover doesn't have provisions for the crankshaft position sensor. The 92 harmonic balancer is different because the snout is longer. The snout on the balancer is longer because the timing sprocket on a 92 doesn't have the reluctor wheel for the crankshaft position sensor. Exhaust manifolds ,lower intake manifold, valve covers,heads,and a few other things are the same