There are two issues through most of Soviet bloc OOBs.
First, the Soviets didn't use ordinary mortars mounted in AFVs, like, say, M106.
I could not find a confirmation of existence of ordinary 82mm mortar on MT-LB carrier in Russian sources, including book with a review of Russian and Soviet mortars. The only 82mm mortar on MT-LB was automatic 2B9 Vasilek, mounted atop (present in oob). According to a Bronekollektsya book on MT-LB, the Vasilek was mounted in such way only during Afghanistan war, in a makeshift way. It is doubtful, if it was a production variant and if it was used by other countries, although there is a photo of similar Iraqi vehicle (possibly local modification as well).
The book also says, that only lately there was developed SP-mortar 82 mm 2B14 on MT-LB, by its manufacturer's initiative, but there is no information, if it is produced or commissioned.
According to Bronekollektsya, Bulgaria produced own 82mm SP-mortar version, but there are no closer information and in each case it should be verified, if they were exported.
The Soviets did develop 120 mm mortar on MT-LB carrier, named Tundzha, but according to Russian Wikipedia
http://ru.wikipedia.org/wiki/%D0%A2%...D1%91%D1%82%29 it wasn't finally commissioned by the Soviet Army. The licence was sold to Bulgaria instead, which made them for own needs and for some countries only (like DDR and Syria). It had a mortar mounted externally in a rear and lowered on the ground before firing.
The second thing is too wide usage of 12.7mm DShK AAMGs on AFVs. Standard armament of BRDM-1 in the game is DShK and SGMT AAMGs, while theywere very rarely armed with DShk (if at all). Zaloga wrote in "Soviet wheeled armoured vehicles", that "some" Soviet BRDM-1s were armed with DShK. However, I haven't seen such photo so far, and undoubtedly a standard weapon of most BRDM-1s was only one 7.62 SGMT AAMG (precisely saying, AAMG variant was named SGMB - for all countries). Russian sources, that I see, don't mention DShK as BRDMs armament. By the way, a sufficient name is just "BRDM", without "1", used in Russian sources. It seems, that the official name BRDM hasn't changed after introduction of BRDM-2.
The same concerns BTR-152, but this time I haven't found any information on mounting DShK instead of SGMB on a standard mount. Only some Afghan Army vehicles were modified with DShK, but it was mounted with its large tripod in the middle of combat compartment.
Michal Derela