After upgrading the shocks on my Savage XL, it was practically bullet proof, except for the front and rear ring and pinion. Aluminum diff cases would probably solve that. I used to jump it at the top of 3rd gear down hill over my head. Tough truck.
Is it diff cases? Im not talking about the case mounted to the gear but the case that surrounds the diff and holds the bearings for the output shafts.. That would keep the gear mesh in check.