 INDIANAPOLIS--BUSINESS WIRE--Allison Transmission Holdings Inc. NYSE: ALSN, a leading designer and manufacturer of vehicle propulsion solutions for commercial and defense vehicles, the largest global manufacturer of medium- and heavy-duty fully automatic transmissions, and a leader in electrified propulsion systems today announced that it will hold its second quarter 2021 financial results conference call at 8:00 a.m. ET on Thursday, July 29. Chairman and Chief Executive Officer David S. Gr 