Friends, I am not recommending that you buy the module, only trying to explain it. The module is a GM solid state amp probably for a 80 vintage Chevy. They are a dime a dozen in Auto Zones, etc. This module was used in the MG black box amplifier for the HEI ignition system in the very last of the rubber bumper production. The black box amp will set you back about $200 but it may be renewed by opening up the lid and replacing the module with a $15 commonly available part. Also in the box are a capacitor and a power diode that rarely goes bad. The HEI ignition is a four cylinder clone of a series 3 XJ6 Jaguar. It is an almost a bullet proof sytem and makes a great MG solid state ignition. Unfortunately you need an MGB magnetic pick up distributor to complete the conversion. These are no longer available through normal parts sources. If you find one of these distributors used, the magnetic sensor is a Jag part and may be easily replaced. These make very neat MGB ignitions and, of course, look totaly authentic.
I would recommend the HEI ignition, but not the module on Ebay.