Does a 1978 MGB Roadster have overdrive?

Some MG's had the (optional) electrical toggle switch overdrive.. rare If its not on the dash you don't have it.

I believe some MG's had the OD switch on the gear lever.

Not all MGB had OD, all RB 1974.5-80 had wiring for OD late model RBs have OD switch on right steering wheel switch - The wash/wipe switch - pull back for OD forward for DIrect Engine # tells OD or NOT, only 20% had OD BLUE metal tag on bottom rear is OD- Laycock gearbox

for what is the on and off switch on the steering wheel right side across from the signal lights? can be for OD?