Would anyone know where to get, new Unut clips that go into the frame to mount the front bumper brackets.

I just mounted a front bumper on a 66 recently and all the bolts that are in bumper are chrome carrage style with square flange area under rounded heads with nuts on the other ends and the the brackets were were just bolts and nuts going horizontal through braces and the frame i used nyloc nuts on my application

I'll bet Ground Up sells those J-nuts since they sell AMK products.

Read this previous post, http://www.chevelles.com/forums/showthread.php?t=243937&highlight=bumper+nuts
Appears there not available new.

Your talking about the nut that attaches to the frame that the rear of the bumper bracket attaches too it think. If so, it is unavaialbe as far as I know, You will have to find one at a salvage yard. AMK makes a nut that is similar but the wrong size.