▁not ▁merely ▁with ▁machine ▁guns . ▁The ▁Caval ry ▁had ▁already ▁opt ed ▁for ▁a ▁single , ▁larger ▁tur ret ▁on ▁its ▁nearly ▁identical ▁M 1 ▁combat ▁car . ▁In ▁December ▁ 1 9 3 8 , ▁O CM ▁No . ▁ 1 4 8 4 4 ▁directed ▁that ▁a ▁single ▁M 2 A 3 ▁be ▁removed ▁from ▁the ▁assembly ▁line ▁and ▁modified ▁with ▁heav ier ▁arm or ▁and ▁weapons , ▁to ▁meet ▁the ▁standards ▁of ▁the ▁U . S . ▁Infantry . ▁This ▁vehicle , ▁after ▁conversion , ▁was ▁re - design ated ▁as ▁the ▁M 2 A 4 . ▁It ▁was ▁equ ipped ▁with ▁an ▁M 5 ▁ 3 7   mm ▁main ▁gun , ▁ 1   inch ▁( 2 5   mm ) ▁thick ▁arm or , ▁and ▁a ▁seven - cy l inder ▁gas oline ▁engine . ▁Other ▁up gr ades ▁included ▁improved ▁susp ension , ▁improved ▁transmission , ▁and ▁better ▁engine ▁cool ing . ▁Production ▁of ▁the ▁M 2 A 4 ▁began ▁in ▁May ▁ 1 9 4 0 ▁at ▁the ▁American ▁Car ▁and ▁Found ry ▁Company , ▁and ▁continued ▁through ▁March ▁ 1 9 4 1 ; ▁an ▁additional ▁ten ▁M 2 A 4 s ▁were ▁assemble d ▁in ▁April ▁ 1 9 4 2 , ▁for ▁a ▁total ▁production ▁run ▁of ▁ 3 7 5 ▁M 2 A 4 ▁light ▁t anks . ▁The ▁US ▁Army ▁sent ▁out ▁press ▁photos ▁still ▁showing ▁the ▁M 2 A 4 ▁being ▁assemble d ▁in ▁July ▁ 1 9