Cast your minds back to July 2007, the standards of training trucks was changed, they had to have solid sided bodies, abs, and a minimum of 8 forward gears (range change).
Nowadays you can take your test in an auto, and get a full manual entitlement. What would happen if you turned up for test in a 6 speed truck■■?
Just re-read the OP. Interestingly, the 8 forward gears was originally interpreted as a range change but, very quickly, a splitter was accepted. So some folks passed a test on a 6 speed split with minimal or no use of the splitter. A nice powerful truck would motor along happily without the need for the “half” gears. Bear in mind that the trucks were still empty at this point. (I wish they still were - but that’s another issue!)