I just happened to notice, after I pulled the pump out, that the block is marked 599 on the sides of the valley. Can anyone tell me what this means, whats unique about this casting number, the good the bad and which castings are more desireable?

599 is from '92-'93 6.2L/6.5L and is the one to build for power. Probably has a higher alloy content in that series.

I thought the cast number was behind the driverside head on a boss on the block.

So how did this block get into my '94? Could it have come from the factory? This truck has a mixed history to say the least, it was originally a salvage due to water damage, and the guy who had it before me bought it from a guy who did all the restoration work...which he didnt' know the extent of.

If you've noticed there's a cast date on most engine parts. Most of mine are a year before production(spring '93 for my '94). I'd like to see the block cast number on my '94, it would be nice to know for sure 2929 or 599. It just has raised beads where you saw a number. I'll look when I pull the engine and tranny on it as soon as I finish with the '93. (have to have one to drive)

And 1994...

All 1994s have 599 blocks??

OK, i am still confused about the block casting numbers...i have read that the 599 is the "one to build for power" . i have also read that the 506 is "the enhanced" one cast by navistar and has the higher alloy content ?? the term alloy is just discribing a mixture of two or more metals, so increased alloy content means nothing to me unless i know what metals we are increasing. am i missing something...?
OK, i am probably missing a lot of things...but regarding block casting numbers/ better/worse ect....whick is which...? btw i have what i believe to be a 506 with the navistar logo in the valley...but still not sure what it means...http://www.dieselplace.com/forum/images/smilies/cool.gif

the "enhanced" 506 blocks from '99-up have more nickel in the block and are thicker.
the 599 6.2 and 6.5's don't have oil spray holes are thicker and have more nickel. that is what i've been told. don't Cyber-Slap me if i'm wrong.

here's a picutre of the raised beads spelling out 599 on the valley wall.

This does not shed much light on what i know yet...lupy6.5 does that mean there are pre 99 "506" unenhanced blocks? Unless i am not reading my julian date correct....it seems to indicate it was cast on oct 10 1998 so it would be a pre 99.....

'97 -'99 are sapposed to be the oil channel/ weak mains block from GM. What year did AM general start making their own?

are all the 506's done by navistar?

Google it, look for pdf's

from what i understand if it is a 506 but it doesn't have the international harvester logo in the valley it is not an enhanced block.

from what i understand if it is a 506 but it doesn't have the international harvester logo in the valley it is not an enhanced block.
lolol....mine is a 506 navistar logo'd block julian dated J108 meaning 1998. but according to lupey6.5 it should'nt be "enhanced" till after 99....back to the drawing board....maybe it was one of the first enhanced ones...? i dunno anymore

maybe they just didn't get to putting them into new trucks until 99 1/2 as far as i know if it has the navistar logo it is supposed to be enhanced but someone here should be able to set me strait.

They changed a few things in 00, and in 01 I believe the casting went to Navistar.

IMHO, there is no block better than the other except that the early 506 blocks (97-99) are a bit less desireable.

The casting number doesn't mean a whole lot either. While there is only one version ea of the 599, and 141, there are severl versions of the 506.

What years were the 141 used?

What about the AM General blocks, I guess '02 or '03 and up? I hear they have some improvements too, anyone know the specifics?

What years were the 141 used?
Keep in mind there were really no definitive time lines, but 95-96 and possibly 97's had these. I don't think there is much difference at all. Near as I can tell, the OPS being mounted in the valley below #7 intake runner was the only major change.

Does anyone know anything else about these 141 blocks ?

I have to agree with JK on blocks. The one block that I had cracks in the main webs was a 94 599. I also ran the crap out of a 97 block with the oil cooled pistons, but junk aftermarket silvolite pistons cost me that block after a piston disintegrated. By the way, the main webs on that 97 block were not cracked.:eek: