katwalk, not real sure about how to go about mounting a spare tire inside your step side box but if you want to check out what the general offered as original equipment for the fleet side in bed spare tire bracket, click on the below f/s thread link showing the P13 option removed from a 68 C/10 551 50th truck. Mel
http://67-72chevytrucks.com/vboard/s...d.php?t=812375