There’s a lot going on with that lamp.
1 .As I posted under let’s build a 67 Etype
The base chrome bit and body of the car are both a crap shoot
2. The repro socket and lense fitting from the big repop is upside down!
3. It looks good in your hand BUT it’s terrible
I used the socket part only and the wires from the socket
Even the lense was no good
Best to make a rubber channel gasket but not original
Clean up your old unit
It’s much. Much much better
Not an option. it’s been hammered a bit and is uneven, the original lens has several cracks in it that PO super glued. You got a socket? SNG site says NLA
I took apart the new one for parts and threw away the rest
Another waste
Look close at the Lucas lense
It can only go one way
On the original the breather hole is facing down for moisture
The repop is up!
So water can come right in
You can’t flip it!
Its not an unfamiliar story for a great number of After Market parts. Its rather gobsmacking that the manufacturers of many of the rubbish parts being flogged can’t just copy what existed and worked, rather than try and punch above their design ability and make changes.
It looks like there is plenty of meat on the fold over tabs, outboard of the existing holes. You should be able to bore new holes at the 3.5" mark, small ones the size of the screws. Measure the car’s holes to get them in just the right places. Then use a cutoff wheel to remove enough of the tabs for the speed nuts to fit, or alternatively source longer speed nuts. Where there’s a will…yada yada.