Just left dealership. 5.7 oil pump around $60.00 6.1 pump $250.00 and 6.4 pump $100,00. Does anybody know what fits what like will a 6.4 pump work on a 6.1? What is the difference between the three?

If building a 5.7 or 6.1, use a 6.1 oil pump. I have heard of a lot of aftermarket pump failures. I am not sure on the 6.4 pump.

Im using a Melling 10342 with 6.1 spring in my 6.1. Ive heard the new 6.1 pumps from the dealer are made by Melling. Used to be able to get a new 6.1 pump for about $95 now they are north of $200.

I've got a Melling in mine for no particular reason. I'm sure it will be fine, just don't use anything less than a 6.1 pump.

A 6.1 has squirters. A 5.7 does not. I really didnt like seeing my oil pressure north of 85lbs at WOT when the squirters were plugged. Several times a year you hear about a filter gasket blowing out and a near wrecked car. What makes the 5.7 pump so bad?

Volume.

Plus, the whole oil pressure situation is weird when you have to take into account the MDS system.

I've only ever bought 6.1 pumps and never had an issue.

I've never seen a filter gasket go, but that certainly makes sense.

But a stock non-vvt 5.7 oil pump should be good for a stock short block with mds delete and a mild cam, spinning moderate (6,000) rpm, right?

with the melling pump being around $170, that is a number I can deal with. The 6.1 pump lists for over $320 if a dealer really wanted to stick it to ya