Based on the paint condition of the piece itself(missing/rubbed off, chips, etc.) and the ultra bright black numbers, I would venture a guess that the original 3752 either rubbed off or was wiped off and a black permanent marker was used to reapply the number and a "5" was used instead of the original"3". Remember, they only made 5500 of these and a 5752 would be over the limit. This is only my observation on this.