Ok, I think people are confusing two different types of spacer.
The one Iain has, goes beneath the inlet manifold and has a row of 6 holes, right?
And the OP is looking for a 5/16ths spacer, which generally looks like this- correct?
Truth is, I don't know anyone with a VQ25DD with a manifold spacer, and don't know if they are the same plenum. Good luck OP.
Heres one for sale: linky