Good luck finding that missing drawer. Will you be happy with the restore effort if you can't get that drawer????
Even assuming you can get that drawer from new from Snap-on, which I would highly doubt, it's going to cost a fortune; perhaps as much as you would pay for a whole Snap-on toolbox of that size that doesn't need a restore. But that's a rare box, so finding another exactly like it is not going to come up every day. Finding the missing drawer used will be even tougher.
Perhaps if you have some serious sheet metal skills you could make a matching drawer???