ran303A Toploader transmission is a manually shifted gearbox desn built in three-speed and four-speed confurations, introduced in 1963 by the Ford Motor Company to replace the BorgWarner T-10. It was used in most Fordstoploader 3-speed tremec rat ran rab rac hef t150 transmission 2-3 synchro assembly with rings, springs & keys fits jeep gmc chevy & ford '63-'86 with 33t 2-3 rings (1at91j-2.5a)