The jack mast and base plates for 66 and 67 that I have seen are more of a "D" shape, not a "t" shape. The base plates and mast are common and used for alot of Chevy models from those years. The jack bumper hooks are "model specific", and will be stamped with the model info.
On page 317 of the 66 assembly manual it shows a T style mast for the Wagon. D shaped mast for the rest.
Also shows a strange spare wheel for aluminum brake drums which bolts to the outer diameter of the brake drum. It was option P20 and was canceled.
Option P20 Aluminum Brake Drum Equipment-(Spare Wheel & Tire Stowage) Page 317 in the manual