Aluminum LS 1 identification help.

[Tim john---]

Good morning Folk's First time here and first posting. I have an LS 1 engine that I am trying to identify so that I can offer it for sale accurately. It is an aluminum LS 1 engine and the cylinder heads have 339 K cast into them and the block casting number is 12550592, I also have a set of cylinder heads that have 706 0212 MK & 830865. In reference to the engine, it has what I belive a ZO6 intake manifold, a ZO6 cast aluminum oil pan w/ sump and ZO6 fabricated exhaust manifold (it is missing one side). I do not want to assume the engine is all ZO6 Corvette without checking with someone more educated than myself on these newer engines. I am looking to part with it to help fund my goals of putting an overdrive transmission in my 67 GTO along with a robust rear end. If someone can help me out in identifying what I have please do chime in when you have a free moment. Thank You.

Tim john---

[SHines-IT]

Block Casting number is LS1. I do not know anything about the heads, sorry.

[shady milkman]

if it was a ls6 it would have the 243 casting on the heads. you have a 706 which is a 5.3 liter truck head.

[shady milkman]

so you have a base ls1 with aftermarket parts

[shady milkman]

this is the difference in pans...the corvette pans are known as batwing pans as they have those protrusions coming out


the z06 and the 01-02 f bodys came with the ls6 intake manifold shown down here

the ls1 bellow looks the same but notice the egr tube connection on the neck of the intake

[Tim john---]

Thanks guy's thus far. What I have is the complete engine AND an extra set of cylinder heads. I kind of thought that the extra cylinder heads were from a truck, thanks for confirming that one.

The bigger question is the engine and its components. The numbers on the cylinder heads on the engine are 339K with the block casting of 12550592 and the block has LS1 cast right into the backside so no mystery there and it is a 5.7L. The ZO6 only came with this style of oil pan, intake manifold and exhaust manifolds.

The engine that I have is identicle to the so called "Bat Wings" as in the photo above (C5) for an oil pan.

My engine also has a pilot bearing / bushing in the crank and as far as my understanding goes only the manual transmission vehicles were machined for such, therefore I assume my engine is for a manual transmission application as well ?

I however would like to confirm that it is a complete ZO6 engine which I belive it is but would like confirmation and or correct identification. Thank You.

Tim john---

[shady milkman]

Thanks guy's thus far. What I have is the complete engine AND an extra set of cylinder heads. I kind of thought that the extra cylinder heads were from a truck, thanks for confirming that one.

The bigger question is the engine and its components. The numbers on the cylinder heads on the engine are 339K with the block casting of 12550592 and the block has LS1 cast right into the backside so no mystery there and it is a 5.7L. The ZO6 only came with this style of oil pan, intake manifold and exhaust manifolds.

The engine that I have is identicle to the so called "Bat Wings" as in the photo above (C5) for an oil pan.

My engine also has a pilot bearing / bushing in the crank and as far as my understanding goes only the manual transmission vehicles were machined for such, therefore I assume my engine is for a manual transmission application as well ?

I however would like to confirm that it is a complete ZO6 engine which I belive it is but would like confirmation and or correct identification. Thank You.

Tim john---

339k is not a gm casting number for the GenIII +s ...that sounds aftermarketish. one of the easiest ways to tell if it is a oem ls6 243 heads is to look at the valvesprings ...if they are yellow you got yourself oem stock 243 heads..if not ..no dice

[shady milkman]

12550592 block casting number is a 1996-mid 1999 ls1 cast.


ls6s had casting number # 12559378

so sorry bud no ls6

[shady milkman]

339 casting is a older style CSB casting.

[Tim john---]

Springs are yellow (paint daub) bee hive style. I belive this engine is a 1999, Tag hanging from it reads "99". Is there anything else that I can look more closely at to help in this mystery. Thank you so very much for helping me out here.

I just want to be able to be accurate in my description when I sell it. I want to sell it to help fund a project for my GTO (overdrive transmission and rear end).

What is a "CSB" casting ?

Tim john---

[shady milkman]

chevy small block..like a Gen I casting number ..that is why i am confused.

[FasstChevys]

Springs are yellow (paint daub) bee hive style. I belive this engine is a 1999, Tag hanging from it reads "99". Is there anything else that I can look more closely at to help in this mystery. Thank you so very much for helping me out here.

I just want to be able to be accurate in my description when I sell it. I want to sell it to help fund a project for my GTO (overdrive transmission and rear end).

What is a "CSB" casting ?

Tim john---

If it's a '99 engine - they didn't make the ZO6 yet.

Can someone back up/refute this? I don't think the ZO6 returned until 2001.

[SHines-IT]

If it's a '99 engine - they didn't make the ZO6 yet.

Can someone back up/refute this? I don't think the ZO6 returned until 2001.

C5 Zo6 2001-04

[Tim john---]

Thanks once again for keeping this thread alive guys. I belive this engine to be of 1999 vintage and my only reason for saying so is that it came from GM with a paper tag on it with a big "99" written on it. Is there a casting date that I can look for, where and how to decipher?. Interestingly enough this engine came with the (I belive ZO6) exhaust manifolds, a ZO6 intake and the bat wing oil pan. This was/is an R&D piece and like I mentioned earlier perhaps this engine and or its components were R&D prototype stuff for the then up-coming ZO6. I do not know nor claim it to be, just trying to figure out its accurate application as to not mis-represent it in any way. If someone can explain to me how to post photos I can do so and if someone would like me to send them to them and they can post for me that would be great as well. Thanks again.

Tim john---

[shady milkman]

Thanks once again for keeping this thread alive guys. I belive this engine to be of 1999 vintage and my only reason for saying so is that it came from GM with a paper tag on it with a big "99" written on it. Is there a casting date that I can look for, where and how to decipher?. Interestingly enough this engine came with the (I belive ZO6) exhaust manifolds, a ZO6 intake and the bat wing oil pan. This was/is an R&D piece and like I mentioned earlier perhaps this engine and or its components were R&D prototype stuff for the then up-coming ZO6. I do not know nor claim it to be, just trying to figure out its accurate application as to not mis-represent it in any way. If someone can explain to me how to post photos I can do so and if someone would like me to send them to them and they can post for me that would be great as well. Thanks again.

Tim john---

the engine has been modded so really anything zo6ish on it will not be original. the ls6 intake which was on the z06 is very common mod for ls1s. it came stock on 01-02 camaros and i believe vettes too. the batwing oilpan is universal on the c5s.

[TmaxicanA]

thanks shady. i did not know that if you had 243 heads it was an LS6 block..

[shady milkman]

thanks shady. i did not know that if you had 243 heads it was an LS6 block..

it isnt

243s were used on ls2s and on ls4s also

[TmaxicanA]

did the 243 heads come on LS1's? or just LS6 and newer designs?

[Y2KPewterSS]

did the 243 heads come on LS1's? or just LS6 and newer designs?

243 heads did not come on LS1's. The 01 and 02 fbodies got 241 heads, which were LS1 heads.

[TmaxicanA]

ok thats were i got myself lost. i kept confusing 243's for 241's