The sequence of registrations seems to point to some connection between Heavylift and TransGlobal
RP-C8015 B737 TransGlobal
RP-C8016 B727 Heavylift
RP-C8017 B727 Heaviylift
RP-C8018 MD83 TransGlobal
RP-C8019 B727 Heavylift
RP-C8020 Belfast Heavylift
...... or is it just a coincidence?