From the VIN of the 83 TE which I know was a grey market car ordered specifically, picked up in Europe and a couple months later shipped to the US.

550 trailer coupling (с 01.03.1965)

I just deleted a pile of picturse I took when stripping it and can't find one of the rear bumper mount holes, I just went out and looked at the nose I’d chopped off and still have from this car and there are holes that the US bumper shocks will fit, absolutely.

I'm not sure as to the reasoning you’re getting at as far as US bumpers after Euro hitch removal. The Euro hitch is basically a bar across and behind the Euro bumper and mounts to the two vertically arraigned outside bolts (these are two bolts fixed by a steel spacer; they are loose inside the frame. On each bumper mount the inside single fastener is a stud welded in place and not removable) of the bumper mount, the bumper is attached to the hitch.

There are holes in exactly the same position and size as the holes for the US bumper shocks, the Euro hitch has tubular extensions off its rear side, towards the front of the vehicle, which extend into the channel box of the frame. Up inside the channel box two holes are drilled and two bolts and a plate secure those bumper extensions to the wall of the frame's channel box. The hitch is rated at 2500kg as a result of this mounting design.

So I think that the holes are there because the hitch requires them rather than as an ability to mount US bumpers with shocks, that's just a coincidence. I've also had an 84 300D NA Euro with a 5 speed which also had a hitch and that wasn’t exact but very similar with the mount design having extensions that went into the holes also used by US bumper shocks. I'm all but certain that vehicle had holes in the front bumper mounts because I use a tow bar which I attach to the front of the vehicle after removing the front bumper, with which I flat tow the vehicle. I’m pretty observant and think I would have noticed the lack of holes, but I guess anything is possible. For sure there is always something to learn about these cars that you didn't know before. I'm completely surprised of the lack of the bumper mount shock holes; I'll be looking at every 123 chassis for this difference from now on though. And 126's for that matter, I pulled a massive Euro hitch of a 126 gasser that had holes because it had extensions attaching to the frame through then but it also had other extensions external and below that attached to the frames box channel also.

Here’s a pic of the bumper/hitch with the extensions: