I thought only the loopy quads had the spilt top tube (where it meets the seatpost?)
off bmx museum
1979-early 82 Looptail mild steel/Chro-mo Quad
1982-early 83 Chro-Mo Quad
1983-early 85 Reynolds Quad (rear down tubes meet at seat mast)
1984-early 85 Freestyle Quad
1985-93 Reynolds Quad (rrear down tubes continue past the seat mast onto middle of upper tubes ala Looptail Quad )
1994-95 Cantilever brakes/threaded forks Quad
96+ all Canti brake/Threadless fork Quad
The rest is FUJI Junk IMHO