Please define "These cars". Please re-read my post above - in 1985 or any year up until 1991/1992, AMG NEVER put their own serial # or a new VIN # on a car they modified. The original MB VIN is all there is. AMG at that time was an independent tuner of stock MBs - they were not a manufacturer who could change the VIN of a car. The only #'ing AMG did in the 80's related to the DOHC 32v engines that started with a stock M117 block and AMG added their in-house designed quad cam heads to those blocks. On those rare engines, AMG added a stamp onto the valve cover with a sequential #, displacement, engine builder ID #. That's it. If your car has a 32v DOHC M117 AMG engine, please post a picture.
Please define "original AMG crossover" - no clue what that refers to. MB did not take an ownership stake (about 10%) in AMG until 1991/1992 and did not complete the acquisition of 100% of AMG until 1999.
If you really want us to comment on your car, you are going to have to post about 50 pics of the exterior of the car (show the AMG P/N stamp on the front spoiler, the side skirts and maybe rear bumper skirt - can't tell from the pics), engine, suspension (shocks/springs), exhaust, interior. Show pics of the original wheels that you had to swap.