Wotcha and welcome mate...
Good trucks the 2.8's...we have 4 of em!!
As for rot...chassis should be clean...in many years of playing with these trucks have never welded an A series chassis yet!...
Body...check the lower front panel behind the front bumper, and rear end of sills (more so on a sport than a lwb in fairness)...thats about it on these..
Sometimes worth removing the wheel arch spats and having a clean up, treat, and touch up behind them and then refit, as sometimes rust can start there where the crud sits and its better to catch it sooner than later.