My upper left door hinge spring is gone and I found one locally, What's the easiest and best way to install the spring?
Can it be installed with the door still on the hinge?
Here's the spring in question.

https://www.ebay.com/itm/1-UPPER-DOOR-HINGE-SPRING-ROLLER-FOR-1962-1965-DODGE/381967615136?fits=Year%3A1963%7CMake%3APlymouth&hash=item58ef0b44a0:m:ms4hBkY3qsuCVlTfT0fTk3w&vxp=mtr

This is how it's done with the spring in a vise.

1. Clamp bottom of spring with hinge loosely attached. Photo is S shaped spring, but C shape should be similar.

2. With one hand use a large crescent wrench or similar to turn the spring from relaxed position A to stressed position B. The force needed is maybe about 30 ft lbs or so.

3. With other hand raise hinge to hook the spring in stressed position.