This comes up every now and then and I don't recall seing all of this stuff pictured before.
The military had to have a way to test the components on water proof sealed electrical systems. They had an adaptor set that allowed testing. I found one for a low price the other day. Here is the lead that goes between the distributor and the spark plug wire allowing a regular inductive timing light to be used.
http://img256.imageshack.us/img256/4...stleadtyp5.jpg
Here is how a tach can be hooked up. This screws into the cover through the little inspection hole.
http://img80.imageshack.us/img80/118...stleadtzt9.jpg
Here is the entire kit. Other leads are for generators, power to the distibutor and the regulator in older 25 amp systems.
http://img61.imageshack.us/img61/711...testkitjk5.jpg