Do the training/test with a RR gearbox as it opens up alot more options for you. Many new trucks are synchro mesh and even automatic these days but most of the older trucks will have crash boxes. It only takes a few hours to master, going up through the gears is a piece of piss, and once you realize where your revs should be when down shifting it will become easy enough for you. Took me about 2 hours before I was able to drive unassisted, and was ready to test after the next lesson...
Once your confident double clutching the RR box, see if they will teach you to drive it clutchless. You will be thankfull after working 12+hr shifts lol!!!