No I never tried a 70 series. I will add that on two cars that were lowered the rear end ( 8 3/4") seemed to be offset to the left side about a 1/4" and with someone in the back seat I did get a small amount of rubbing on right turns, not bad though and it didn't do it without some one in the back so with a taller tire you may get a bit. I went with a 5 speed to drop the rpms. What gears are you running in that Dana and is it stock abody width?