World Class means it has bearings on the gear clusters instead of the brass bushings used on the non-WC tranny. It has a torque rating 30 lbs-ft. less than the WC T-5 transmission (that has a max of 300lbs-ft). The World Class T-5 is still a weak tranny used behind V-6 and 305 max V-8's in Firebirds, Camaros and Chevy S-10 Trucks.
Big Dave