I just measured my mid-size:
Outside to outside : 51" wide
Inside to inside : 46"
Bottom inside to inside : 44" flat on the bottom, 45" about 1/2" off the bottom (above the rounded seam where the side meets the bottom)
Front to back inside to inside 32"
Front to back inside to inside bottom : 31.5" flat on the bottom, 32" about 1/2" off the bottom (above rounded seam where the back meets the bottom)
**Note: don't forget the radius where the sides meet the back and the 45 degree angle supports between the tailgat and sides
Now that I have explained it clear as mud, feel free to ask for any clarification.
Outside to outside : 51" wide
Inside to inside : 46"
Bottom inside to inside : 44" flat on the bottom, 45" about 1/2" off the bottom (above the rounded seam where the side meets the bottom)
Front to back inside to inside 32"
Front to back inside to inside bottom : 31.5" flat on the bottom, 32" about 1/2" off the bottom (above rounded seam where the back meets the bottom)
**Note: don't forget the radius where the sides meet the back and the 45 degree angle supports between the tailgat and sides
Now that I have explained it clear as mud, feel free to ask for any clarification.