I peeked into my valve cover through the oil hole, and low and behold, triple-box headbolts...indicated 12mm headbolts. So either I've got a 12mm, or someone drilled and tapped it out to 12mm which would be unlucky. I was really dreading tearing into that thing and finding 11's. Now I'm half tempted to drop the oilpan and see if it was a jetta tdi swap and look for oil squirters.
Someone MAY have put 11mm gas stretch bolts in it, but I had an engine out of an 81 that was 12mm.
I had considered that. I suppose the only way to really find out is to pull one and find out, yeah?
Pull one out, or get the code off the block..
You know where to find it?? It's kind of a pain to see, but basically it's behind the bypass hose that goes form the head to the water pump.. Stamped to a flat spot right below the head gasket...
Went out and looked, and I had a hard time finding the casting number. I did find that it was made in Germany, and still has green paint on it. (Green means good right? haha)
Green like money!!!

Here's a pic of a bare block to help you.. The first 2 letters are what you need.. Kinda hard to make out, but inside that green circle is an "ME" on this one....
my bet is that it has 11mm head bolts.. most 12mm engines came with cam baffles
my engine has triple square bolts, but i KNOW that they are NOT 12mm..
whats the crank bolt look like? is it 17mm 6pt? or 19mm 12pt?
also, does the back of the block say D, 16D, or 1.6D?
D = 1.5D
16D = 1.6D with 11mm head bolts.
1.6D = 1.6D/TD with 12mm head bolts.
again, as was mentioned tho, find the engine code. they sometimes start with a *