most foreign truck ,volvo,man,mercs seem to have a synchromesh box,so apart from more gears,it's similar to driving a car,when you change will depend on weight and terrain. The "british" I drove with twin splits,SA ,Foden have a kind ofconstant mesh box,similar but a little more forgiving than the old 'crash' box. Once you get used,you won't even need your clutch,apart from starting/stopping. As Cats says,unless your going up a steep hill with a load,then you can skip a few. When your changing down,if your wagon wont go faster than 30 say in third,then you won't be able to get third going down if your going 35,then you won't be able to select that gear on a non-syncromesh box. Just a matter of practise and getting used to engine noise. If it's a crash box,then check with rev counter what speed the wagon will go in each gear,then you'll know you can't change down if your going faster