I'm coming back to this because I found a
useful article discussing post-WW2 use of tank turrets in static defenses. Some that are mentioned would have almost certainly still been in use during the Twilight War, such as Austria's M47 and Centurion turrets that were in use in the late 1990s, Denmark's Centurion turrets that were scrapped under the CFE Treaty, Finland's T-54 and T-55 turrets that were installed in the mid-1980s, Italy's Sherman and Pershing turrets that started being scrapped in 1992, and the Soviets having various IS-series and T-54/55 turrets in static defenses until the late 1990s.