They do have some reinforcement in the attachment areas. All of my 124 except the 500E had at least on broken/ cracked tab that i had to repair. It has been quite a few years but I remember using various techniques to repair them. Thin aluminum plate with the original tab sandwiched ( longer screws needed) when it was a small crack I just used a soldering gun on the plactic and welded it back together.

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92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )