Only guessing Sqn, is it the small boxie' shaped pieces with a circular hole in it's base, welded inboard from the sills? The purist 'Body Men' out there will put me fully in the picture over this one, without doubt!
I thought these were used on the assembly line as locators, and then as reference points if 'jigging' was required during any major repairs? The standard scissor jack with the 147, has a plastic grooved block, which engages with a predetermined section of the vertical sill edge measured front or rear. I have marked the approximate positions, with not too obvious silver arrows on the underside of the sills, 4 in all.
Using the jacking beam, I am able to locate this under the rear of the front subframe, this provides a really strong lifting area, prior to putting stands under the sills vertical edges, with hardwood triangular blocks inserted, which I have covered with cut outs from the sidewall of an old tyre as previously mentioned. Rear wheels are chocked, handbrake on, and a pair of extra stands with blocks, located at extra points, just in case!!!!
As said, I take wheels removed for tyre fitment, makes me
when I see these ??? guys at tyre stations just shoving a trolley jack under the side of a motor.