torgue converter. It sits between the motor and the trans.
Take it to a trans shop and see what they say. A rebuilt or used from a junkyard won't cost nearly as much from a trans shop.
Scott-2013 F350 with a lot of tires.
2013 40' 4-slider stoneridge 5th wheel coming in at 15,400; 2015 Lincoln MKC
Previous Truck 2008 F250 6.4 with lots of upgrades and a suspension upgrade from Torklift International StableLoads