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Utility Bed Rail - T-Slot nut size - M12 16mm slot


Active Member
Oct 2, 2018
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Denver, CO

M12 T-Slot Nut for a 16mm slot ground down ~1-2mm in height. Only found these available at Mcmaster-Carr. 16mm length bolts are perfect. 25mm would likely be max when you add on extras to avoid bottoming the bolt out. If I were to do this again, I'd just cut metal plate into squares, and tap them to M12...but I thought I'd do it "properly" for too much money.

Long winded version:

I wanted to add more attachment points to the bed rails than the 2 supplied cleats per side. I have some future plans for these additions. After measuring the rail and the supplied cleats, I have found these to be the best ones available....which are still not a direct fit. I'm mildly frustrated that the size of these rails are not a standard size for t-slot nuts, nor are they the same as every other bed rail that Toyota, Nissan, Ford, put out. I believe those are all a 9/16" slot.

These are a perfect fit for the 16mm slot width itself. The M12 t-slot nut that you see all over ebay, grainger, zoro, MSC, are for a 14mm slot. Mcmaster-Carr does carry the M12 for 16mm slot, and that's where I bought mine (photo of item attached). Unfortunately they can't be had as cheaply as the standard 14mm slot. These fit perfectly with a slight caveat....the detents cut in the rails for the stock cleats have a little lip that makes the rail slightly narrower than 16mm in those tiny spots. A slightly heavy press with the t-slot nut knocks that lip down...or you can lightly file it down....then it's truly a perfect fit.

The "biggest" problem is that these need to be ground down to a shallower depth. If not, the bolt will bottom out on itself and not lock into the rail (making these out of plate with a threaded hole instead of t-slot nuts would avoid this). A milling machine sure would be nice to make them square and clean, but I took a flapwheel on my grinder to take 1-2mm off each, and now they work perfectly. Zero slop, but slide through the rail very smoothly.

Just thought people would like to know so you don't have to buy extra cleats that are likely going to be $40 bucks when available (basing off of other brand's stock cleat replacements).

Note: You could likely use a 5/8" slot T-nut with a 1/2" bolt, but everything else on the truck is metric, so I stuck with M12. You would also have to grind down the 5/8" nut a bit.

IMG_20190329_232128825.jpg IMG_20190329_232444389.jpg Capture.PNG


Active Member
Dec 23, 2019
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This is awesome! Would love to see what you all are using these extra cleats for.

What about the smaller track on top? Anyone use that for accessories?

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