Насколько массово Уралы поставлялись в соцстраны, и при этом не в их вооружённые силы?

As far as I know, in Hungary, all of the Ural trucks were imported for the army. In 2005, there was a big dismantling when anybody could buy vehicles from the army, the Urals were also sold to private owners, who use them in forests. Nevertheless, Ural is a rare truck here, Zil 131 and Csepel D-344 are much more common (and, of course, PV3S at the northern ends).

375й же, почему общая модель?

375Д в 1990 уже не выпускался.

375ДМ до 1991 года и после пожара на заводе двигателей КамАЗа некоторое время.