I have just come back from the SEMA show (largest trade show in the world) in Las Vegas and visited the Cosworth USA stand to enquire about YB spares and the guy there said that they have now started production of all aluminium YB block and handed me one (it was light). He said that it saves 51 lbs in weight over the regular one and has head bolts that go all the way down to the bottom of the block advantage being the probs with different expansion rates between current steel and alloy head don't apply so better headgasket life. Just thought I would share that with you unless of course it is common knowledge and I am the only guy that didn't know it!