I wouldn't recommend using these old jacks to actually change a tire. Use them just for show in the trunk. You can carry a modern, compact jack in the car incase you have a flat. If this isn't an OE car, you could get away with an "incorrect" jack. Other less popular cars probably came with a similar setup and would be cheaper. The differences would be in the mast length, jack hook and possibly the color of the mechanism/base.
The mechanism/base can be repainted, the mast length difference will be hidden in the trunk and if the jack hook is close to the same size, many won't know the difference. You should be looking for a "T" mast...not a hollow tube mast. If your car came with a space saver(standard on convertible...required option with 15" wheels...optional on all others) then you'll need to find a decent original one. I think Ford also used a space saver spare in some cars. A Ford piece might be cheaper then a Mopar piece and would look similar.
