That’s the casting number for “cylinder head”. The info you’re looking for is here.

http://www.ford-y-block.com/cylinderheadchart.htm

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I have a 292 y-block engine with cylinder heads with the number 6090B on the boss just under the end of the intake manifold. What head is this and would it be a good breather to match up with the ECZ-9425-B intake manifold? Thanks.