Hi Stu,
Yep, the Japanese stuff is 1/150, much closer to British N's 1/148 than the Euro 1/160. It'd be nice if they developed some more European looking trucks, as although Hino, Isuzu and Mitsubishi trucks are seen in the UK, they're nowhere near as common as Scanias, Dafs, Volvos, MANs etc.
I've mainly picked them up from exhibitions, there's normally a couple of stands selling them at big shows like TINGS and Warley. eBay and Osborn's Models have also come in useful, I tend to choose models on their "bashability" than particular livery or bodywork
jo