390 w/open chamber heads

moper said
"I understand what your saying about "zero decked" but then again, that's what it refers to, Zero decked for that particular application.
As for your underlined statement above, I'm a bit baffled. Its a simple fixture for older machines to set deck heights, and correct the 90° deck angles and crank/cam 45° to decks."

CP - You may be baffled because your assumption is the shops own one because it's easy to get. My assumption is they don't but still claim to be able to square deck. usually they are the ones that use a level to set the block's position... I knew one place that had a special mark on the level because the floor's slab had cracked under the miller and it wasn't level itself anymore... "as long as I level to that mark they're fine..."

Depending on the block, the machinist, and the milling equipment used this could be a good or bad thing as there is no reference to setting a deck hieght or correcting any relationship of the deck to anything else.

Well, honestly I'm not baffled, just seems odd you would imply there is no way possible to reference deck height or squareness when you obviously have the knowledge and awareness of how to do this stuff correctly.
A simple process of indicating in the plate and a measurement to it does both of these things.
Yes, I agree and am aware most shops that make claims dont have the skills or equipement to do this. My block fixture was the first thing I made when I bought my surfacer.