V6 Non-Balance Shaft Engines with Hyd. Roller Cam. Limited High Performance Street Use - Needs Intake, Headers, 2500+ Stall and 3.73 to 4.10 Gears. Mild Rough Idle - For Carbureted Applications. Balance shaft equipped 4.3L engines were introduced in '92 but GM continued to produce the previous version until '94. Non-balance shaft 4.3L's ('85-'94) shared their timing cover with the small block Chevy V8 engine. The balance shaft 4.3L's timing cover is noticeably taller than the non-balance shaft version.