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.



Here is how a tach can be hooked up. This screws into the cover through the little inspection hole.



Here is the entire kit. Other leads are for generators, power to the distibutor and the regulator in older 25 amp systems.