Rochester built 137 DIFFERENT B series carburetors. Some have the screen, some do not. The online manual is a GENERIC manual; and is not correct for MOST series B carbs. It is an excellent guide, but one needs the parts specification bulletin for each carburetor BY TAG NUMBER to be sure of anything.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop