This page gives details of the aircraft types that were offered or promised to the Paraguayan Air Force, but not delivered, cancelled official orders, and types have been falsely reported as being in service.
Cessna T-37C
The supply of 12 ex-Brazilian Air Force T-37Cs was proposed in 1979 to replace FAP T-6 trainers, but the US government vetoed the deal.
Tweet and Dragonfly: The Story of the Cessna A-37 and T-37
Mil Mi-8T ‘Hip’
A Mil-8T was reportedly delivered in May 1992 and written off in 1994. This machine was actually leased to the Policia Nacional and not the Air Force.
Northrop F-5E Tiger II
A deal to obtain 12 F-5E/F aircraft from Taiwan was under negotiation in the late 1990s, but could not be completed due to lack of funds and air base infrastructure limitations.