Engine block differences?
 

I recently had to replace my block due to a warped engine block. I own a 2003 350z touring the mechanic i took it to managed to get a 2006 350z block to replace the old one with. Car ran great for a couple weeks then again blew the head gaskets. Could it be due to the fact that the block i replaced it with was from a different year? Is there any differences between the 03 block and 06 one?

The blocks are the same , unless the 06 block was from a Rev up. Minor differences from what I understand, but will not cause a head gasket failure

Did you check the heads before installing on the new block? I mean, so that they were completely flat?

Br,
Al

An 06 with an automatic trans will have the same block/head design as an 03. If your mechanic sourced the engine from an 06 with the 6MT (A.K.A. Rev-up longblock), you will have problems mating it up in your 03. The engines from 05.5 and 06 years with Automatic Transmissions didn't have any major issues. This was only for the Rev-up longblocks which were only offered in 6MTs.

If the engine you recently replaced suddenly blew a headgasket, it could also have occurred from an improperly bled coolant system...which lead to an overheat scenario, even if your coolant temp. sensor was sending nominal readings. These cars are notorious for being difficult to remove all the air bubbles from the coolant system. There are guides/explanations available on these forums. Make sure your mechanic is aware of the nuances on the 350Z, especially when it comes to bleeding the coolant system.
Good Luck!
-Icer

Seems like it is a little late for that. Hopefully repairs were made with a warranty.