Ignore the rust on the left. That'* 6 months new stored in my garage.

Left pump was $26. Right pump was $29.





Left is NEW. Stamped "GMB Japan" on the housing and shaft.
Right is NEW. AC Delco. Rock Auto was the vendor.

You be the judge.

I installed a pump like the left and it failed again within a week. Started makin' bad noise.

I say Delco... I assume it would have a warranty?

Christ, that thing looks like it'd be pretty rough, probably a lot of cavitation as well.

Let me complicate this for you.

I run a 10% underdrive water pump pulley on the Zilla. Kinda makes the choice a bit easier, doesn't it?

Haven't we had suspicion that our WP cavitate at higher speeds anyways? Would a 10% underdrive help cooling @ high speeds given the system is in top notch spec otherwise?

Right side. The increased length of the impellor blades will increase flow, The curvature of the blades will reduce cavitation, and the peice is cast versus stamped.

Undrive pulley will cause the pump to turn slower.

10% was way too agressive for any car even remotely considered a streetable car. I had to make a major step in thermostats to run it (heavily drilled 160). And I had no cooling issues whatsoever before then. 5% would have been better.

The point being, you get what you pay for. The water pumps pictured here are a good example of what 3 bucks more will do for you.

the one on the right looks like the one i would use.
the shaft is also flush with the center of the blades , and blades looks like it will better coolant flow..........

So did our cars roll off the line with the right one?
Its been too many years and water pumps ago for me to remember accurately, but I think I would noticed this difference back then.