The 1A3 tachometer sending unit is designed to screw into the engine's mechancial tachometer port (Lycoming/Continental style). Included is a 0.156 diameter tang along with a six-foot harness. Franklin engines require a different tang. The 1A3 TSU is designed to work with UMA TSU tachometers only. 

This version has a Lycoming/Continental style connection.

Specifications

Dimensions: 4.5 x 1.3 in, maximum

Harness: 6 ft