IIRC is an Internet acronym that could mean:
If I Recall/Remember Correctly
If I Read Correctly
If I Really Cared
If It Really Counts
Isn't It Really Cool
I seem to recall a factory overdrive unit for a 1954 Sedan Delivery (automobile enclosed driveshaft drivetrain and I think chassis). I will check when I get home and will edit this message.
[There was an RPO 315 Overdrive Transmission w/4.11 rear end for 1954 Chevrolet Automobiles. This comes from an Oct '54 Truck Data Book that lists models/option/accessories for trucks and cars. Because it is a late 1954 Data Book, it is possible that this is referring to an open driveshaft. Earlier A-D years do not appear to have a GM RPO Overdrive Transmission.]
Truckstell made an aftermarket torque-tube overdrive until for automobiles and, I think, light trucks.
