Just a datapoint: lots of czech(oslovak) devices contained large amounts of MH54xx military grade TTL logic, because it was more readily available than lower-sp

Just a datapoint: lots of czech(oslovak) devices contained large amounts of MH54xx military grade TTL logic, because it was more readily available than lower-spec MH74xx (and I believe that both soviet-made KL555xx-series and east german D1xx-series of SN74xx TTL logic clones didn't have different reliability grades)