Hey Rick,
I only see that Edelbrock only make 1 style water pump with different finishes, reflecting different part numbers
For 1970-92 429/460 (3/4" pilot shaft) 8866 8876 N/A
* Left-hand inlet, includes new backing plate. Fits all 1970-92 429/460 V8s in passenger cars, trucks, vans and motorhomes. Has heavy-duty 3/4" ball/roller bearing. Dimension from block surface to hub: 5-1/2". Inlet diameter: 1.98".
FORD FE - Standard Rotation
I would lean more toward a blown gasket