michael,
amber lense on the tail lights was not legal here in the states when these cars were built.only a few would ever check the part number to see if you used the correct lense. the first set i bought with outside screws came from tiger tom back in the late 70's. i know he drilled them. weren't the amber only used in europe? did they use them on UK cars? i have to agree that they do make the rear look better. speaking of amber lense, i have two NOS wipac back up lights with amber lense for the fastback. they are the top mount. i found that they were only installed on hunter range cars sent to france.