ok, so my friend has a 00 Z28, i was looking for his head casing #s and they werent on the passanger side... looked like they had been machined off and i was like thats really wierd... so i go to the other side and it the 843 (?) casting, not 241 like my 00. how do we find out what year block his car has? he plans on spinning close to 7k and would like to have oil return.

 

in 00 they had 853's on the early models. thats what my car came with (bought in april 00)

 

but they had the blocks with good oil return?

 

PCV system? if thats what your talking about, no. i thought only the ls6 blocks got the new PCV system. as long as your not getting blowby, you shouldn't have a problem

 

I'd be more worried about the stock rod bolts then the oil return being most people upgrade the oil pump while they are switching out cams.

 

what im talking about is actualy how the oil flows through the block. 97-99 LS1s had just two holes to return the oil, later ones had a larger area, if you dont kn ow what im talking about you probably cant answer my question haha. i hope someone out there knows what im refering to

 

I modified my block and the rear cover.

I belive the 2001 and later blocks are the blocks that have the "opened" up rear area. You'll also want to look into replacing that pump.