I have a question about the proper #'s on a water pump. In the Chevrolet by the numbers, for 1970 BB water pumps it shows 3931065 for early and 3969811 for late. When is the line between early and late?
Every thing on my engine is date coded J for october. The water pump I have is #ed 6263707 the book showes for a 1972. What Should the water pump be on my engine?:confused:

The 3931065 was out of production around April/May of `69, so all `70 Chevelle big blocks got the 3969811.
There may be a few exceptions on some very very early `70 cars, but I wouldn't think so.