Where is the weak point

No experience with the trunnion or other manual parts, but the ring & pinion has been the weak point in my years of automatic 8 3/4 footbrake racing. Stripped the teeth a few times. I had no issues with solid Spicer u-joints and steel billet rear end yokes even though they were for 7260 joints! OEM style yokes can spread over time. FWIW, I believe the hammering of constant hard 2-step launches is just as hard on a rear as a stick. Vehicle weight and hard hooking are major factors too.