The last ones were retired in 2003, that makes 20 years in a cold and possibly wet storage. And we don’t produce the needed 105 mm rounds anymore. To me this is nothing more than good will to get rid of them.
Don’t we have any Kanonenjagdpanzer hiding somewhere? They need 90 mm rounds … 
Yes you are right. The main modernization of this tank (produced in 1962 - 1975) is the T-62M carried out in 1983 -1985. Leopard A5 - 1987 modernization. Not a new version, namely the modernization of the previously upgraded Leopard A1A1 (1975), which was a modernization of the Leopard A1 (1970), i.e. upgraded Leopard 1 (1965).
If I’m wrong about a few months, then correct me. 
