I'm not sure I know what you mean by "new fender sides". I have contemplated cutting the top portion off some old fenders to bolt above the flat part of the aluminum. I can think of no purpose other than appearance. It would be easy tho, I might try it. Honestly, I built this rig to work on my property as a hunting rig/tractor. Did some web searches and caught the bug. Now I want to fab a crawler. Today I bent up a swing away spare carrier, it goes on Mon. when I buy more mix for the MIG. Tomorrow I'll do the rear fenders. I don't know what's next, maybe shorten up the top and button it down behind the seats to the boxes lip and I think I'm done. I know "you're never done", but I have 2 other Trackers to screw around with.