Later “Standard” Cast Iron (usually) Shelfback stem
Starting in the early 1950’s, Standard changed both the design of the spout and the internal design of the faucet. From the outside, the hot and cold valves appear identical to the earlier version, but they are different. The giveaway is the spout. If your Standard cast iron sink has a rotating lever to operate the drain, cross handles and looks JUST like the photo below, this is your stem. There is a fairly rare version that’s on a porcelain sink, if the bonnet nuts are the same as #86-760020, then this is your stem. Stem has 22 splines, 7/16″ diameter shank, and the length is 2.94″. The original pictured handles aren’t made anymore, our #80-0100 handles will work, but are bigger. There are two different seats used in this faucet application, if the opening of the seat has a square shape milled in it for removal, use the #86-648360 seat. If the internal opening of the seat has a hex shape to it, you’ll need the #86-648350 seat.