oh man, you dont even know how long it took me to figure out what the threads were!!! i searched sooooo much and this question was asked ALL OVER the net but nobody had any answers. i planned on posting it once i figured it out just for that reason but i guess i forgot!!!
anyway the thread pitch is a 20MM x 1.5 thread pitch http://www.summitracing.com/parts/ear-9919fflerl
there ya go bud. all i used was some teflon and it works great. no leaks. good luck