im thinking when i do my cage i'm going to tube the rear frame as well. i'll be using 2" od hrew... is .120 enough or do i need to move into a thicker wall tube?

.120 is by far the most common thickness in roll cages and tube frames.

with well thought out triangulated mounting for the suspension points .120 should be plenty strong enough. just build your mounts to spread out the loads. are you running a linkage rear or leafs?

i thought .120 would be plenty if i tied the whole the whole thing into the cage. i'm going to run leafs but eventually it'll be a 4 link.