Never seen heat shrinking at connectors from Ford; doesn't mean they don't exist, but they are certainly not common.
Agree. I think shrink tubing appeared in 1962, 63 or 64. It was too new to be adopted by Ford in that time frame.
Any spade connector that has exposed metal is a grounding connector.
I cannot remember any 65 or 66 Mustang with a spade lug. There are ring lugs with internal teeth used as grounds, the dash comes to mind.
There are at least 2 sizes of bullet connectors: one of which is very common and is compatible with standard trailer connectors.
The two common sizes are 0.156 in dia and 0.187 in dia, the latter being very common on 65 and 66 Mustangs, and thru 73 on most connectors. It seems that the Ford standard was the 0.187 in dia, GM and Mopar cars of the era used the 0.156 dia pins. I base that on a GM heater blower motor that "appeared" in my junk pile.
A smaller pin, I estimate it at 0.050 in dia and being solid, seems to have been used on door jam switches after 1967.
Multi-pin connectors are an entirely different story. A smaller pin/socket was used to make the connector blocks themselves smaller.
Jim