Airfix White Half Track M3A1 (A02318) The M3 Personnel carrier was developed from the four-wheeled scout car. During WWII, more than 41, 000 vehicles were produced by the White Motor Company. This version came with the enhanced M49 machine gun ring mount over the right hand front seat. Between 1942 & 1943 all M3 Half-Tracks (standard & A1s) were continually upgraded. These improvements included a number of drive train, engine, & stowage improvements.