The reason I was looking at dimensions is I am currently having issues with my rear tail lamps complying for rego.
I was told by the powers that be that they do not pass current laws in NSW.
I played around in my spare time (none) and worked out the finner points.
I even made one of Jimmymacs Mercury lamps but decided against it, in the end I ended up with the Fiat/Ferrari lamp that where one off several lamps run on the 40's
These have Hella ADR approved lamps in the centre, the lens I machine out of acrylic to replicate the original dimentions,I used a lens paint in the rear of the lens to give colour.
I put a pollished disk in behind the lens to make it look right.
The polished rim I made out of 316 s/steel.
Jim