Its a weird set up. I believe it takes a 3/8" extension (I guess it could be 1/4", but for some reason I remember it being 3/8"), just the square end of the extension, and you put that in and then twist and pull. Its a strange set up indeed, and it will come out with a little finagling. The new radiator I have has a wing nut on it and I like that SOOOO much more.
I guess our radiators are different. Mine has a wing nut and is also shaped like a 3/4" hex head so you can just slap a socket on it. Twist a quarter turn and it drains out the drain hole in the bottom.
2004 Impala LS - got some mods sold!!!
2009 Subaru Impreza WRX STI
NAIOA moderator Still Imp'n, just in a different Imp.