The thing about used housings is that with the passage of time almost all of them will see the two long sides taking an inward curve.
I know that WILKINSON did have these reproduced but I have not ever seen them in person. I do know, even though Steve himself denies this, that each corner of the car has a different housing. Steve only reproduced two of those and is telling everyone the left front and right rear are interchangeable, etc.
I believe the DOT requirements for these markers was that they be parallel to the car's centerline. With different front and rear fender curvatures, each housing had to be different to keep the lenses parallel. The difference of each housing's angle is something that no one, however, will ever notice.