Do you know if was ISU-152 used in assault gun role or as indirect fire piece?
ISU-152 was kept in Soviet Army service as late as 1972, mostly in indirect fire role (they were equipped with dial sights, the range was ~15km) until enough 2S3 came in service, although it was a stop-gap measure with some limitations, for example, the gun elevation angle was not high, and therefore it could only fire in a relatively flat arc. Secondly, ammo load was low for such role and extra shells had to be placed near the SPG, and once the ammo rack ran dry, it took about an hour to replenish it. Alternatively, the shells could be handed to the loader one by one, further reducing already a non-exceptional rate of fire, resulting in lower effectiveness.
9P122 and similar earlier ATGM carriers were not used?