Small block heads with no casting numbers

Here is a lifter I've never seen one like it. I'm pretty sure it's hydraulic it has a oil hole in the side. I tried to see if they squeeze down like hydraulic do and they don't very much. I mean very very little. There is little to no preload. Are these some sort of odd ball solid lifters? Something is all out of wack tho because the cam is on full lift on this lobe and the valve is barely open. What do yall think?