w45= 4 speed 2wd version of the w50-58   they would be in 90 ish delivery pickups,  like auto parts stores use,  the very stripped down no a/c or creature comfort   el  cheapo trucks


if like the G45  to G52-G54  they could be made into 5 speeds  simply by adding the 5th components, 


i know this cause i asked marlin about a G45  back in the spring