peterc said:
.......The case says "Made in Germany U.S. Zone"
I stumbled rather than scampered into this thread while googling this lens for som other reason. U.S. zone should mean no later than 1948 or so, when the BRD was constituted, closely followed by the D.D.R. to the east. The Leica II was still being sold new in 1959, so the Leica version of the Culminar may have continued into the 1960s. When did the market for new Leica screw items dry up? The Leica look-alikes from other countries may have had a longer life and kept demand up for a while.
There's a lens list with the Exakta versions at
www.ihagee.org (follow links through equipment and lens list). The dates given there are 1950 (8.5cm), 1951 (85mm) (both manual diaphragm), and 1955 (manual preset diaphragm, not relevant for a leice screw version). The next steps for Steinheil lenses in Exakta mount were auto-diaphragm (still polished chrome late 1950s), then black finish with "zebra-style" focusing ring (auto-diaphragm 1960s). The 85mm lens was never produced in these newer Exakta versions.
The Leica version might have preceded the Exakta version. Ihagee didn't really get going until 1949-50 (the new Kine II), the factory having been totally destroyed in the 1945 Dresden air raid. About 50 000 of the 1930s Kine I were produced in the few years up to 1949, allegedly from parts and tools salvaged from the ruins.
A lifespan, then, possibly from late 1940s, definitely throughout the 1950s, and maybe a few into the 1960s.