I don't think so. They are used to hold the front,rear,and sides together. You might be able to make the side bars shorter to fit the trucks. I'll try and get a pic of how it's put together. I tried it on my 521 as is and it was too long front to back.
Looks like you should be able to trim the side bars to make them shorter for the pickups. You'd have to trim the center bars as well so everything looks right.