Rear Tires Suddenly Lock Up Going 65

Of course! Still could be a collapsed hose, that actually makes a lot of sense now. Would also explain the lack of power feeling just before they locked up. I may have enough power to not even notice a dragging brake until it heats up and really starts to drag. I was going to do a brake job while I'm at it since they're in bad condition, probably just change the hose for good measure, flush the brake fluid, machine the drums, new quality shoes. But I'll wait on that and experiment with everything the way it is now to try and replicate the problem. Also, the drums were "ok" coming off but nothing seriously tight.