The only parts I never "broke" on the savage were the cam steering bell cranks, arms, skid plates, shock towers, c-hub things (that held the axle carriers) and the threaded aluminum shaft that holds the bulkheads together.
Every thing else, bent broke or stripped at one point in it's life. I have to say though, it was very durable. Mine was an old school 21 savage core. Bought it as a roller.
Never had the stock engine.
The trans even held together for 20+ gallons of use. The only thing that gave me fits was the olds school two speed that had a single pin. That was during gallon #2. I replaced the gear and put two pins in (as was the suggested "mod" of the era) and it lasted until I got rid of it. Never had the trans open again.
The TVP's even held up. I did a bit of grinding to fit an engine in and drilled a few extra holes for stuff. I did finally tweak them though. Jumped off of a 20 foot tall dirt pile at a refinery... it jumped further than I had anticipated and missed the downslope of the side of the pile. Ended up doing a direct lawn dart on the front end into a concrete slab... that one cost me the tweaked tvp's, engine plate, engine mount, spur, aluminum bars that hold the engine plate...
Sorry... kind of rambled...