So, I picked up an '04 L59 for my next swap, and after looking it over, the thing has definitely had a massive amount of work done to it in the past, and I'm starting to get curious. It looks like heads have been off (They are 706s with the castech mark, but I'm thinking they might be newer replacements?), and additionally, when I tried to figure out the manufacture date of the block, I found the number on it looks like no GM date code I've ever seen. Wondering if anybody has any idea what this is?




Looks like "05 A68" to me, but I can't tell, and it's not the typical 4 digit format I'm used to seeing.

Also, if anybody knows how to tell if the heads are a newer Castech replacement, I would be very happy to know.