Mopar 1974 Seatbelt Interlock Diagnosis tool

Hey all,
As crazy as it sounds I will be putting in the seatbelt interlock system so that it works on my 1974 Challenger. I think it's a pretty neat one year item. I found this diagnostic tool up on Ebay, you would plug your computer module into this tool to see if it still works or vice versa to diagnose problems with the system. Presumably the Dodge dealership would have one.
Has anyone seen one of these before? Do they come up very often? Seems expensive, but would be a very cool garage item, and in my case, actually useful!

http://www.ebay.ca/itm/74-75-MOPAR-P..._qi=RTM1963930



Here is a video from Chrysler showing how it worked, also pretty neat. This must be one of the first microchips in a Mopar car?

Author: Canuck74