WTB: Cargo box for luggage rack C4 convertible

[Thomas ZR-1]

A friend of mine is looking for a very special cargo box for his 1992 convertible. He purchased the box with the car many years ago but unfortunately the box is lost now. He can`t find it anymore. Maybe some of you can help me to find this as a used (or new) part. There is a manufacturer sticker on the box: DOT Products in Little Rock but I don`t get any results from google...I hope you can help me with this.