Some of the tubes, especially the chrome ones, need the tips ground down on a grinder to start in the block holes.
I use a 1/4 x1. 0 long inch bolt stuck into the top of the tubes to drive it into the blocks, I do straighten the top part first so it won't bend while driving it in with a small hammer hammer Not a 5lb sledge hammer tsk Once it is in as far as I can safely get it I rebend the tube to fit the block engine mount holes wrench
On your deal you may need to remove that tube and make it shrink back down to original O.D. size to get it in all the way to the stopping rib work scopeshruggy

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)