Has anyone tried the Tuffy 60% lockbox for a silverado under the rear seat?

[SemperIratus]

I have been looking at one of these to replace the stupid I-Bar storage bin under my rear seat, as near as I can tell the dimensions (based on Tuffy's website) are identical. I am not worried about having to drill mounting holes in the box if it comes to it, however it really looks like a drop in fit. Any thoughts?

Silverado 60% underseat lockbox