Stage 1 - These pumps use new original equipment castings, but are machined and assembled by Stewart Components to our exacting standards. Externally, Stage 1 water pumps appear stock, and are compatible with stock lines and brackets. Internally, Stage 1 pumps are modified for performance and reliability! Recommended for stock, OEM or mild performance applications. All Stage 1 pumps feature: Higher flow and pressure for better cooling. A full one-year warranty. Models with 3/4" ball/roller bearings offer five times the strength of standard bearings. Precision ground fan hub for perfect pulley alignment. Equal flow to left and right cylinder heads. Precision impeller installed to exacting tolerance. Zinc plated rear cover bolt. Stock external dimensions and hose locations. Special water/antifreeze compatible seal assemblyPit Stop USA offers Stewart Stage I Water Pump - Ford 221-351W 16173 at low everyday prices. Be sure to check out all of our products from Stewart Components including Stewart Components Small Block Ford Water Pumps.