Trams of Australia
The F, G and K classes were built for the Prahran and Malvern Tramways Trust (PMTT), the Q for the Melbourne and Metropolitan Tramways Board (MMTB), and the R for the Fitzroy, Northcote and Preston Tramways Trust (FNPTT).
The F and G classes were built as straight sill centre-aisle summer cars with 5 doors on each side (seating 52). This is quite close to a toastrack design, and it must have been unpopular, because in the early 1920s they were modified by removing the centre door to make an enclosed saloon with longitudinal seating. The K class was originally built this way, but was unpopular because it was very rough-riding.
The Q-class trams were built by the MMTB in a plan to quickly increase the number of electric trams in service.
In 1928, these codes were rationalised. The F, G, K, Q and R classes are all single-truck straight-sill, closed combination cars, so they were all re-designated as G-class. Since they were "straight-sill", not "drop-end" like the Old A class, I would have thought they would be harder to board (more steps) than the other design. I am not sure what the attraction of this design was.