You may have a water pump that was intended for an engine without A/C.
http://www.oldsmobility.com/old/67-Olds ... er%20pumpsAre there any differences between Oldsmobile V8 water pumps?
There are actually three different Olds water pump lengths. The measurement you care about is from the gasket surface of the pump (with the gasket removed) to the front face of the flange that the spacer or fan clutch bolts to. The three pump sizes are:
5.947" - all Olds motors with A/C
5.572" - B and C body without A/C
5.072" - A and E body without A/C
Note that the "with" or "without A/C" really applies to the pulley set that you are using. The pulleys and accessory brackets are designed to match the pump, so if your car had A/C and you removed it but are still using the A/C accessory brackets and pulleys, get the A/C pump.
One other item to note is that some HD cooling cars used the longer A/C style pump even though they did not have A/C.