Alex,
re: the Kenyan AF crash ... if the 'National Day' was 22nd July '74 then it was probably '603' as '605' eventually went to Botswana as OJ10.
re: the Botswana crash ... wasn't the date 29th April 1989? It was probably one of OJ4, OJ5 or OJ9 as these are all listed as being written-off.
The Botswana DF seemed to spend some time re-numbering everything, presumably trying to hide aircraft losses (?), so after OJ4 (the original one) was lost, there was another one which became OJ4; the same happened to OJ5 and OJ9.