i would just remove the biggie adapter , do away with the oe oil cooler adapter and lines (the oil adapter just slides off ) ,and whats left is the metric threads then just spin the pte adapter on
if you already did away with the oil cooler then the rjc biggie adapter is just a thread adapter that just needs to be spun off leaving you with the metric threads to spin the pte adapter on
if you plan to keep the oil cooler you need the nut , for that you should have posted in the parts wanted forum