Severe vibration at 60 mph

On my 2009 Tacoma 5" lift with 35 12.50s I get a severe vibration at exactly 60 mph. I have had 2 alignments and balances with no change and today I took it to the shop and had them check it over, the bearings and all of the suspension components were in great shape. They did find that the nut on the passenger side upper control arm ball joint had never been tightened back down!!! I'm guessing after the lift. there wasn't any threads showing through the grooves on the castle nut so they probably turned it on hand tight but forgot to tighten it with the rest. With that being said and with all of that being checked and tightened, the problem is still there and got a little worse but still at exactly 60 mph... any ideas... please help