Well for the Kangeroo’s, there are shit tons, from Stuarts, Rams, Priests and even Churchills and hell even shermans. Generally the idea comes from a lack of APCs, (Mostly M3 Halftracks as the UC wasnt suited by this point to be an assault transport.), but an excess of tanks, hence relatively easy conversions by ditching the turret. As far as Im aware, the only model that wasnt well received was the Stuart due to very thin armour and those converted ended up as artillery tractors.
Kangeroo's

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The M3 Lee used as an APC
As for the Soviet Conversion of the M3 Lee, from what I understand, it was a limited run of the earlier models of the M3 Lee before the US sent them later versions which didnt have side hatches anymore. However documentation of them is a bit dodgy of specifics, 17 men carried is the normal figure stated for its capacity, however its not stated if this includes tank riders as well as those inside. Otherwise its also mixed info if the its the Turret which was removed, or the casemate 75, or both even to make space for more people inside. I have read however that 10 men armed with SMGs could be fit inside plus the fighting crew, though phrasing isnt perfect. This could be where the 17 men figure came from, since as we see with later cold war doctrine with the likes of BTR’s and etc, the crew is counted as a part of the squad its carrying.
As for official documentation, good luck, I suspect a lot of it came from in the field modification, however its a thing I read about in multiple accounts so Im inclined to believe it. Saying that, it could also be a misunderstanding spread over the years, see above the mention of 10 men with SMGs being able to fit inside, that comes from the official testing of the M3 Lee by the soviets, hence its not impossible that was taken out of context and spread all over. Its also a real issue to distinguish between when the men were riding on top of the tank vs when they were inside of the tank, though there is certainly accounts specifying inside the tank, making note of only the earlier models with the side doors could be used effectively as APC’s.
TLDR, Its highly likely, however finding proof beyond anecdotal first or second hand accounts is near impossible, the closest Ive found is the official soviet testing reports for the M3 Lee when it first arrived. As we should all know by now, finding photo proof of soviet equipment is a nightmare unless you have unrestricted access to the Kremlins archives.