Here is a used 6 1/4" dia balancer for the internally balanced Sb Chevy engines. Has part number 066004 on it. Good shape.
Scat 4340 I-Beam 6.0" SB Chev Connecting Rod, 7/16" ARP Bolt, 595g., 2.100 J.
PRW 1940001 SFI Billet Alum, 6061 T-6, Chev SB 383-400 1970-85
PRW 1940000 SFI Billet Alum, 6061 T-6, Chev SB 383-400 1970-85
Manley 2.02" Head Race Flo Intake Valves Fits LS-1 / LS-2 (LS-6 Head) SB Chevy