My understanding of Chrysler transmissions in the 39-40 timeframe is that fluid drive (FD) was only available on the stright eights. In 1940 the Saratogas, New Yorkers ands Crown Imperials came standard with a three speed mahual transmission, but FD coupled with OD was a $27, option. The Borg-Warner OD had the electric kickdown feature, called "Cruise-Climb" by Chrysler. Needless to say very few eights came without this option, but it was not offered on the Travelers. The FD transmission had three forward speeds and OD just like the sixes with OD, but the sixes did not have the FD. I have a 1940 Saratoga and you can shift through the gears normally or just leave it in third, stop without depressing the clutch, and then accelerate away, albiet leasurely. I understand that the same setup was an option on the eights in 1939 and 1941, except that in 41 first gear was blanked out. I find it to be a very flexable setup. One advantage of FD is that it eliminates sharp jerks on the transmission, the differential and the drive shaft. My Saratoga (top of the Chrysler line in 1940) will cruise all day at 65.