I have a small 28x10x12 "top box" style toolbox for the back of my Sidekick and I wouldn't mind seeing some pics of your toolbox hold-down setups. Right now it's just loose and I'm worried if I ever got in an accident or a rollover, it could bean somebody in the back of the head and kill them. I was thinking of drilling though the floor and putting in some cargo tie-down loops but the stock sheetmetal isn't exactly strong. Any suggestions? Thanks

First, the carpet and rear seats are removed from my kick, more camping gear space and use for transporting trannies motors etc. I have an ammo can that I have drilled thee or four holes in the bottom of and run button top bolts up from the bottom (no unbolting from under neath if the box is locked). The box has riveted padlock mounts that fit through the slots in the opening handles. Under the box I have used some adhesive to bond a sheet of nitrogen foam (craftstore sourced) to keep vibration down but I don't know how much it actually works. Lowes sells washers with rubber gaskets on one side to keep water out. just be carefull to place the bolts on either side of the frame rails.

http://www.cardomain.com/ride/817265/4

Still has the carpet in this pic but it's gone now. It does rattle a bit but holds my gear.

The entire floor in the rear of my sidekick was rotted out so I had to weld in a new piece of sheet metal.  Since it doesn't have the support brace going from one side to the other anymore I was worried about long term strength (even though my 210 lbs could stand on it fine).  So I just went to lowes and bought a 4x8 sheet of 3/4" plywood and had them cut it to my dimensions (they do it for free).  I think it was 31"x41".  Then I used 2x4 and created a frame that sits on top which acts as storage and support.  Since the wood sits over the curved part (where it decends to the floor behind front seats) and all the way to the back door (where its more reinforced on the body) it spreads the weight out well and does a great job.  Gave it a couple shots of black spraypaint and it look good.  Then just drilled through wood and used deck screws to mount to floor (be careful not to puncture tank or lines).  Mine actually has three bays.  Two bays on the side are measured off to perfectly fit the quickcrete 60lb sand bags for winter traction.  The space left in the middle is a perfect fit for two of the small plastic rubbermaid style tool boxes walmart sells for like $15.  Currently the boxes have locks and are screwed down but I am still worried when summer comes I'll have to pull them out so someone doesn't try to remove them by cutting through my new top.  I have considered a sharpie message stating they are bolted down.     But some teenager will probably try anyway.  So next I am thinking about some other type of latch system. 

Here are the strap loops I use on my camping trailer for hold-downs.  Pick them out at most hardware store, use a big fender washer on the back side.  Then I used kayak straps with them.  Haven't had a change to outfit the back of the Tracker with them yet.