I had a custom shop make some steel t-nuts a few years ago after I got?my?KF700sp. Today, I found that I have extra 2 short t-nuts and 3 long t-nuts laying around unused. I use it with Kreg automaxx clamps, see pictures below.
As I mentioned before, the automaxx clamp pulls the stock a bit when clamping it. As long as you have the plywood block placed against the stock being clamped, the stock will not move at all.
The short one is 70mm long, the long one is 120mm. All have 5/16"-18 thread.
I can offer it ($25 for short one, $40 for long one, plus shipping), I am in Ontario, Canada. I can get the shipping quote from Canada Post or your choice of carrier like Fedex and UPS. I heard the shipping cost from Canada Post is cheaper than Fedex and UPS here.