There are still a couple of active glider pilots in South Africa who
moved south in the 1970's - you might try posting to one of the club
sites there. In the 1980's in Johannesburg I bought a Jantar that had
been imported from what was then Rhodesia and there weren't many others
left there even then.

From recent reports, there are no current gliding operations in
Zimbabwe (surprise!!), but a local pilot told me there may be one or
two still in Zambia.