I'm reporting
I've found a page
http://ser-sarajkin.narod2.ru/ALL_OU...SuPzTrl001.htm , apparently OCR-ed from some magazine (Tekhnika i Vooruzhenie?), in Russian, but with many photos (right arrow leads to further parts).
It says, that there were many experimental designs starting from 1932, but there's no mention, that any of them were combat-tested (these early developments were for T-26 and T-28, not KV).
Only in 1942 there was developed first successful PT-3 (ПТ-3) roller. According to
http://russianarms.mybb.ru/viewtopic.php?id=1158 it was accepted in 4/43, but the previous page says, that they were first used in 11/43 near Kiev. Mass usage was from summer 1944.
It could have been also mounted on KV-1 or IS-2, but photos are rare and presumably they were less numerous. By the way, this KV on the photo is late model, probably 1942. We could add such units, from 1944, but they should be used in heavy tank formations only.
There's no mention in article about IJ-2 designation.
So, it seems, that unit 87 PT-34 should start later (along with its formations), and a better name is T-34 PT-3. On the other hand, there's no reason to wait with T-34/85 PT-3 (unit 201) until 6/45 - I believe they were fitted with rollers since late 1944.
Michal