Is there a difference between 4g54 distributors?

[Superscan811]

which one do I want

It depends on what you are doing.
If you are wanting to "plug and play", it's a good choice. The 2 wires go directly to the coil (just check the polarity) and away you go.

IF you are wanting to do a bit of tinkering yourself with the timing curves, the GJ onwards, Scorp dizzys with the full cap for the rotor button like this..

would be a better option.

The springs are easily accessible and easy to change their tension.

Cheers.

[81GL]

Get the later model one if you are starting it from fresh. The ignition module is in the distributor, so less wiring etc, and as above, they are easier to play with, you don't have to pull it all apart to alter anything.