So I have a engine block with the casting number 53008405, and a date of 6/27/90 on the drivers side. On the passenger side there is a stamped date of 006MX27 which I believe translates to 6/27/1990. It has crankshaft with casting number of 3003453. It had a cylinder head with a casting number of 2686.
From what I know about 4.0's this block casting number should be wrong?? Isn't it as follows?

year casting#
1987-90 53005535
1991-95 53008405
1996-98 53020569

Look here page 9-49.........http://www.jeep4x4center.com/knowledge-base/index.htm

Page 9 of what link? There is a bunch of them there.

4.0 Engine date codes

The date code is on the passenger side of the engine, on the block, just forward and up from the distributor on a machined flat surface.

The digits of the code identify:
 1st Digit-The year (8 = 1998).
 2nd & 3rd Digits-The month (01 - 12).
 4th & 5th Digits-The engine type/fuel system/compression ratio (MX = A 4.0 Liter (242 CID) 8.7:1 compression ratio engine with a multi-point fuel injection system).
 6th & 7th Digits-The day of engine build (01 - 31).
1. FOR EXAMPLE: Code * 801MX12 * identifies a 4.0 Liter (242 CID) engine with a multi-point fuel injection system, 8.7:1 compression ratio and built on January 12, 1998.

http://www.greatlakes4x4.com/showthread.php?t=661

This looks pretty similar to the link Cruiser posted above>> (block , crank, and cam # are there) http://www.jeep4.0performance.4mg.com/tech_specs.html

Try this center of page online repair manuals.......http://www.jeep4x4center.com/knowled...?utm_source=cj

Yeah, I got that already. What I'm confused about is that this block should not exsist. It should not have been manufactured until 1991 as an HO block with no knock sensor drilled and tapped.

Dave, I've done a few HO into Renix swaps and every HO block was still drilled and tapped for the knock sensor. That's not a good reference.

Cruiser, I don't doubt your knowledge on Renix to HO conversions. So let me back up here cause this is going in the wrong direction. Maybe I wasn't clear what I was after and thats my fault. I have the 1990 block as I described at the beginning with a #3003453 crankshaft. Which is what it supposed to have, the crank is trash so I pulled a motor from a 93 sport that had the 53008405 casting on the block identicle to my 90. As I researched it on the web the 53008405 casting is reserved for the 91-9* whatever and should have a crankshaft #53010411. I pulled the pan on the 93 and low and behold it has a #3003453 crankshaft which should not be there acccording to Rockauto/Oreillys/Autozone books. I am the second owner and I know its the original motor for this vehicle. So that got me looking at the block casting numbers because I was confused at this point. So I have a 90 block that should be a 91+ and a 93 block with 88-90 crankshaft parts.
Could I be safe to assume the crankshaft in the 93 work in the 90 block since they are both #3003453 cranks?
Does Chrysler always break the rules on casting numbers???

I built one engine using parts from 3 different engines, HO and Renix. Go for it.

Sounds great, but which main bearings do I use?

SEALED POWER Part # 7211M because it came out of a 93 block....or

SEALED POWER Part # 4289M because its going in a 90 block?

Just took the crank to get it machined, so I need to order my bearings.

The ones for the block.

Thanks for your help.

There's a reason I know that..........LOL.

Been there, done that, got the tee shirt??? LOL