Exhibit 99.1 Allison Transmission Announces First Quarter 2024 Results * Record net sales of 789million∗DilutedEPSof1.90, which includes 0.13impactfrom14 Million of Non-Recurring UAW Contract Signing Incentives incurred in the quarter * Refinanced Revolving Credit Facility and Term Loan, Paying Down 101MillionofOutstandingDebtINDIANAPOLIS,April25,2024–AllisonTransmissionHoldingsInc.(NYSE:ALSN),todayreportedfirstquarternetsalesof789 million and first quarter diluted EPS ...