and a vent tube that is soldered shut

Stock application there would have been one of these on the right side (as if seated on bike) of the speedometer

and including the battery (not included) weighs just about 1 pound

2 1/4" deep

CAD Plated Triumph Tachometer Plug - 1969 and Up Triumph 1/2-20 L.H. Thread Subcategory_Hubs and a vent tube thatThese tach plugs let you remove the tach drive hanging off the front, left side of your unit Triumph engine and plug the hole with some class. CAD Plated Steel to match the look of your cases and prevent rusting. Made in the USA. For unit Triumph motors 1969 and Up with a left hand thread.