Vintage Cars: Positive Ground, triumph tr3, wire colors

Question
What is the easiest way to determine whether my newly acquired Triumph TR3 is set up for positive or negative ground?  It was originally positive (British)but the generator was rebuilt and there is no battery in the car.

Answer
It's likely still positive. (1) The ignition switch wire should go the negative terminal on the coil. (2)Battery terminal posts and connectors are slightly different sizes. My car is not close by to check, but I think the negative is the larger post (check your own regular car). If it's positive ground the ground strap (to the frame) will only properly fit the positive post. And vice versa.

Unfortunately you can't check the generator output until the car is running (which needs the battery!). But there's a nice wiring diagram at http://www.advanceautowire.com/tr24a.pdf complete with generator wire colors and voltage regulator terminal letters. That's for positive ground.

JJ