The 2H is a 6 cyl diesel engine, inline fuel pump, 100% mechanical other than EDIC control, and glow plugs and related accessories.

The 2H puts out about 110 hp @1800 and 177 ft/lbs of torque somewhere near 3000-3300 RPMs.  It has a very high rev scale compared to a 2F Gas engine, it actually redlines higher than a 2F engine and has a similar feel.  Because it is not turbo charged, it is easily affected by altitude, likewise when upgrading to larger tires, you must pay very close attention to axle gearing, like with all diesels.

Dimensions wise, it actually has almost identical dimensions to a 2F and weighs roughly the same as well.

They were available in North America for only two short years, in Canada in 1986 and 1987.  They are found with either a 5 speed manual transmission (H55F) or an automatic, the same one (A440F) found in FJ62s.  It was considered to be "the replacement" for the 3B engine which was available in Canada through 1985 in 40, 60, and 70 series models.

The 12H-T is the factory turbo charged version with major differences being  piston skirt cooling for the turbo, and a different, direct injected head and accompanying parts.  Otherwise it has the same block and bolt pattern as the 2H.  It was never available in the USA, and was available in HJ61s from Europe and in other countries.  The 12H-T puts out roughly 130 HP and about 230 ft/lbs of torque, almost identical to a 2F gas engine to get an idea.

Overall, all H series engines are very smooth, quiet, do not rattle much, and are a great application for a truck in my opinion that has not been heavily modified.  Adding a turbo to a 2H is a wonderful addition, even though the 2H never came with piston skirt cooling. 

For more information, see my information on my former HJ60.