The breakdown of the sample gearbox code F4W60L is, as best i remember,...
F = Floor shift [R = Remote as in column shift]
4 = four speed
W = wide ratio. This is the standard four speed designation.
60 = This is the 'series' of the gearbox. It represents the distance between the center of two parts, but i forget which. [main shaft & cluster shaft?] A series Datsun gearboxes came in 56, 60, & 63 series.
L = Long. This refers to the length of the rear extention housing. This is the most common size.
This particular gearbox came from an Aussie [B310] Sunny wagon with A15 engine.

Knowing this, it shouldn't be too hard to figure out some of the other codes.

The MG Midget is a Roadster. A Convertable is a four or five seater.

A US model 'Datsun 210' is correctly known as a member of the B310 family [AKA Sunny in Australia] & the US model was available with a 60 series gearbox & quite possibly the 63 series gearbox as well. The five speed versions were both overdrive gearboxes i believe.
Can anyone confirm?