The ATS 2049432218 Big Foot T4 Exhaust Manifold is the perfect solution for your 5.9 Cummins 1998.5-2002. T4 Flanged Exhaust. This unit is designed to improve exhaust flow and eliminates the common cracking issues that are often seen with similar products on the market. The patented ball flange design allows for expansion and contraction, while also increasing reliability and improving exhaust flow. If you're looking for an exhaust manifold that can provide superior performance and lasting durability, then the ATS 2049432218 Big Foot T4 Exhaust Manifold is the ideal choice for you.