US OOB 12 corrections/suggestions (v.6)

[Pibwl]

Few suggestions of additions:

- M5 High Speed Tractor (from 5/43) - existing M4 HST (#381) was a tractor for heavy artillery, while M5 was most common.

There were also used by the Army:
- Amphibs:
- LVT 1 (combat debute in 11/42),
- LVT 2 (unarmoured, produced from early 1943)
- LVT(A)2 (armoured, produced from unspecified time in 1943, rather later that year)
- LVT(A)2 modified in 1944 with 37 mm automatic aircraft gun on a pintle
- Amtanks:
- LVT(A)1
- LVT(A)4

More comments on LVTs will be in USMC OOB notes.

I'm attaching mentioned pictures of 75mm M1 howitzer on M3 carriage