Both of kits bypass the internal passages.....what's the diff? Is one much ($100) better than the other....Are they both sufficient? Asking in regards to my 528 Hemi thats a street motor.

Out of those 2 kits, I'd use 21001. It will give you better clearance w/ the line coming in the front of the motor.

One thing to be aware of is the oil filter adapter. Kit 21001 is just the plate that sandwiches b/t the stock oil pump and the block. You just need the longer oil pump driveshaft.

Kit 21000 shows the problematic oil filter adapter that a lot of people have had issues w/ blowing out the gasket, sometimes at high speed, and getting oil under the tires...not good.

Milodon now has billet pump covers that have the oil filter adapter built right into the pump cover...no gasket to blow out. They are very nice, but more expensive. part numbers 21205 and 21215.

Forget the 21000 and you couldn't give me a 21001. Those are 45 year old technology. Lets move on. They make better parts today. The 21001 makes the oil pump so long it may not fit in your car without notching the K frame. Either use one of the billet top covers or the 21815 pump.

On my engines I use the 21815 pump and the 21235 cover with top inlet the 21815 pump is 19gpm and suuitable for use from super gas to top fuel ( so says the package) I have never had an issues with this combo. I don't run a Kmember in any of my cars though, but you may need to notch the member if using one.

My cam max HP is @ 6800 and I planned on a 7000 RPM redline, so the 21185 based dual line system is good for 8000 rpm and $800, double the price of the 7000 RPM systems.

Is there a way to use the 21185 pump in a cheaper single line system, closer to the $400 cost? $800 is just outta my budget for this upgrade.

Those were on a Hemi, I wound up going with a line to the front of my world block to make it work. The covers kept hitting the mounts...Tim

Yep, I remember now that it was you (astjp2) posting about that. Both my cars have wedge K members...obviously the hemi mounts get in the way.
The rear inlet cover they call the "hemi" cover...I don't see how it would work unless you have a motorplate and have completely removed the motor mount brackets from the K member.