Geez. I wonder if I'll
ever get this bulb & socket thing right. It seems I've reversed the bulb and socket designations.

The socket in the first pic is a '1/2 minibay'. The 'G3' bulb Alfa uses in it refers to the size and shape of the bulb. The second pic is of a '1/4 minibay' socket that Alfa fitted a 'T3' bulb to and the 3rd pic is a '1/4 wedge' that also uses a 'T3' bulb, in this case, a #194.
Bulb sizes are NOT to scale.