The B series deisels were manufactured by both Hino and Daihatsu. Those manufactured by Daihatsu and can be identified by the letter "D" on the timing cover. Most of the H series diesels came from Hino.
Most diesels in Japan and Canada are 24V and therefore meet NATO military specs. However, Canadian 1985 (85/10) BJ70's and all Canadian BJ60's are 12V. In Europe, all diesels before 1984 and all diesels larger than 4 cylinders after 1984 are 24V except for in the 80 series which uses a 24/12V Series/Parallel switch to allow 24V starting and 12V while running. Australian diesels are all 12V.
The B and 3B are "industrial" motors with sleeved pistons. Instead of boring out the cylinders when rebuilding, the sleeves are replaced to provide new, factory sized wear surfaces. Another nice feature of the 3B that contributes to its durability is that it shares piston-cooling oil jets with the 13B-T.
Canadian-spec 2Hs were never offered with piston sleeves and as a result, can only be over-bored once.
The B, H, and 2H were also used in Toyota Forklifts, Dyna and Coaster buses.