Dana 30 infront. seems pretty good. Dont the newer ones have a smaller front axle??
My 69 cj had a dana 27 and I broke spider gears a couple times, and striped the T14 trans, then put a muncie 4 speed in it. Also split the transfer case in half, it was the old style that had the rear drive shaft off set in line with the front drive shaft. The foot pedals and clutch cable set up also sucked in the '69, they wear attached down on the frame and master cyl was on the frame too. I had the original buick V6 though.