A65's had 26000 hours, A80's, B80's had 22000 hours airframe life but I think it was all lifted recently.
Excaliburs were fitted with 400 Hp IO-720 eight cylinder engines in place of the IGSO-480's and 540's.
I flew both AEQ and XAE Excalibur Queenairs for Air Eastern in the '90's.
Nice aeroplanes, no gearing and supercharging to worry about, shove all levers to the firewall and off you go. They could uplift around 1200 kg cargo and fly 2 hours with reserves at 175 kts.