My Zeiss Ikon Contax IIIa is a 35mm rangefinder camera that was first introduced in March 1951. What differentiates the IIIa from the IIa is the addition of an exposure meter.
Here’s my Contax.

By the serial number of the body, this camera appears like it was made in the early part of 1951. It features the black dial and non-synced flash connection typical of the first models. This one works perfectly and the only cosmetic issue is a slight dent on the lens filter ring. Just above the Contax name is the selenium cells for the exposure meter shown with the flap open.

The camera features interchangeable lenses in a simple but sturdy bayonet mount. Exposure meter flap in the closed position.

The lens is a Carl Zeiss Sonnar f/1.5 50mm.

A camera shop provided cleaning cloth featuring the Contax IIIa.

It may be a bit hard to tell from this scan but here’s a view of the camera from the instruction manual. The camera’s serial number is T 36017 and mine is T 36625. Pretty close so I’m thinking that mine is an early production model.
Thanks for stopping by! I’ll have much more about this camera soon. – Chris