The Yashica FX-D is " The little sister" of the Contax 139 Quartz released in 1980. Still, some people consider Contax to have a more solid feel, plus it adds TTL flash, DOF preview, and aperture readout in the viewfinder among other differences. Otherwise the FX-D has similar features, the same rather small housing, and the same Contax/Yashica bayonet lens mount. The FX-D is well suited as second body for Contax users, since the controls are placed in Contax-like positions on the body. In particular you find the meter control button on the front side. The bottom of the camera contain contact for a motor drive. Upon release one was not available, but it was compatible with the Contax 139 motor drive.
A variation of FX-D was sold as the FX-D SE Quartz. There is no difference between the models. It was often sold with a FX motor drive winder and a zoom lens.