[QUOTE=Bikedued;13384961

"deeper seat tube socket, and with a slot" Sorry but what the heck does this mean?,,,,BD[/QUOTE]

in this seat lug there are 2 "sockets" that main tubes fit into: one for the top tube and one for the seat tube. The seat tube socket on your lug has a long point and that point has a cut-out, shaped not like a heart but a simple slot, AFAI can tell.