Wycoyote

Hello all I'm looking for a snap on top chest to fit the lower roll cab I bought.The lower is a KR 660B it measures 50 1/4 wide and 20 5/8 deep it is red. I have been searching all over it is an older box and they dont make anything close to that size either to big or to small.I would really like to stick with a snap on box maybe someone knows the snap on number for the upper chest that would help in my search.
I got a few numbers from the local guy but no measurements KA 690 - KA 691 - KRA 691A thank you for your time.