[Drew_trak]

First of all, I recommend using 1x2 x .125 aluminum tube for your chassis. We use this every single year (With the exception of last year). It allows for simple connection of gearboxes. One issue may be getting the chassis square. Our team machines 90degree gusset plates and I dont know if you guys have access to a mill.

As far as Chain vs Belt: Belt Is the way to go

My team is only starting to work with belt. The problem with chain is it stretches. Make sure you have the ability to tension your chain. One year, we couldnt tension a .25 chain and it kept snapping whenever we had quick changes in direction. Again, I dont know if anything I said applies to belts. If your team has gotten belts down, Dont go back to chain. They are heavy
-Best of luck