T nut holding rails
 

Not sure if this was posted elsewhere in the forum, I found this company http://www.ttrackusa.com/ they sell extrusions for using t nuts or a standard 3/8 hexagonal bolt for workholding.

Interesting stuff

I don't think that I would use a standard bolt inside T-track because the contact area between between the bolt and the track would be small and the bolt will easily damage the track because of the stress concentration.

Dunno... its part of their sales pitch:
"The key to our system is a standard 3/8" hex head bolt that slides into the track. No more hunting for hard to find T-bolts or special locking pieces"

I guess if that happens and it gets damaged one could ask for a warranty replacement

Pablo, I don't know if you know about 80/20 but they have a similar product and the track seems to be a little more substantial.

http://cgi.ebay.com/8020-T-Slot-Alum...item4ceb59db75

These will not take a standard bolt but carriage bolts work just fine.