145, 153, 214 - 75mm Pack How - I believe, that icon 2111 is better - it had no shield, and relatively shorter barrel and longer tail (a drawing here
http://www.ww2gyrene.org/weapons_pack_howitzer_75mm.htm ).
Until around 1940/41 they were used with wooden wheels - maybe it's worth to split unit 153 to two units, the earlier one with ready 8624 picture.
Unfortunately, publications don't tell when exactly M8 gunbed with rubber wheels was adopted - "large-scale manufacture of the M1A1 pack howitzer did not resume until September 1940", possibly on M8 gunbed (Osprey New Vanguard 131 - US Field Artillery of WWII)
As for unit
44 75mm Howitzer, it might be just pack howitzer (same comments as above) or very rare 75mm Field Howitzer manufactured for cavalry, with the same M1A1 gun, but twin-tail M3 series bed. However, "no significant production" took place until the war, and serial production started in 1/41, and only 349 were made, "nearly a third provided to China", as the cavalry lost interest in towed guns.
Same for
USMC OOB:
30 75mm Howitzer, 123,124,125,145,146 - 75mm Pack Hwtzr.
Between 123 and 124, in 1938-41 there could be another unit added, with wooden wheels and weapon #33 M1A1. Unit 123 also should have weapon #33, not #150 M8.
BTW: I don't know why (newer) weapon 150 M8 FH in USMC OOB has lower range 164, than 33 M1A1 FH - both were in fact the same gun with M1A1 barrel and 45 deg elevation, and 8.9km range according to Osprey (178 of weapon 33 is correct)... in fact M1A1 could be used for all.
Similar situation is with US OOB - weapon 150 is M1, with shorter range. Differences between M1 and M1A1 guns were rather minor - unfortunately, there is no info, when the model was changed (before the war).