According to Jet Airliner Production List Volume 1, (ISBN 0-907178-97-9)
Boeing B707-436 MSN
17713 was sold to Cargo Charter Company as 9Q-CRW
in 1980, it was then sold to Coastal Airways as 5X
-CAU in 1981. It was sold again the same year as CGH
Management as G-APFL and the Aeroplane Store and then Aero Equipment Company both as N9194M. The latter then re-registered it as 5X
In 1983, they stored it at Entebbe, but later that year, they sold it to the Ugandan Govt.
According to the Individual Aircraft History of the Boeing 707 by Buchair, (ISBN 0-9666368-0-5) the aircraft was actually impounded by the Ugandan Govt in October 1983. However it does not say why.
The book states that the aircraft had 60,319 Hours in June 1980 and also had 60,319 Hours when impounded. Whilst this is clearly incorrect because the aircraft was ferried from Brussels to Enteebe in 1982, it implies that this was the only flight during that period.
According to Jet Airliner Production List Volume 2, (ISBN 0-907178-87-1) Caravelle VIN MSN
071 was wfu and stored by Alitalia in 1976. It was sold to Afro Cargo as 9Q-CRU in 1980. It was withdrawn at Entebbe in 1985.