In Svetlana Alexievich's book "Second hand time", a recurring rhethorical "discourse" regarding the fall of the Soviet Union can be summarized as "pots and pans vs tanks and armor". Basically, a whole lot of pro-Soviet voices seemed to make the case that if the world-leading Soviet arnaments industry wasn't used to keep producing arms, it'd disintegrate into poor manufacturers of 'pots and pans' (since tanks would be of less use in a post-Cold War world). While I see that this very much is a rhethorical exaggeration, it made me wonder why there weren't any large Russian vehicle manufacturers that have come out of the military industry.
Compare this to the losing powers of WW2 - Italy, German, and Japan - who seem to all have turned a whole lot of production of wartime equipment into world-famous automobile industries (e.g. BMW, Volkswagen, Fiat, Mitsubishi, etc.) Why weren't the equipment and technological know-how of the Soviet Union used the same way post-1991?
Many factories converted to producing agricultural tractors after the war. I've read documents where design bureaus were complaining that all their engineers were taken away and no one is left to design tanks. It's not like the factories weren't proud of their tank building. Konstruktor Boyevykh Mashin (Designer of Fighting Vehicles) which is basically a huge PR piece for the Kirov factory has a whole section dedicated to peacetime vehicle production after the war.
The factories also went back to what they were doing before the war, like building train cars, locomotives, etc. The few truck manufacturers who were converted to tank production like GAZ continued making trucks.
As for post-1991, all or most of these factories sold their tooling for scrap. Only a small fraction of the Soviet industrial might still exists in former Soviet countries.