1985 500SEL gray market - some questions

[cvgbenzlover]

One of my friends is considering buying a local 85 500SEL with 73,000 miles. The car is amazing looking (dark blue, gray leather). It for sure is a gray market - german on the cruise control, short bumpers, a box with the original euro lights and a set of tail lights (assume the US versions must be different?). The service book is stamped up to 1992 when the car had 32K. Not any other records. The guy wants $6,500. I told my friend absolutely do not buy this car without a PPI !!! for the reasons we all know I am also thinking the price is a little high for the following reasons:
1) needs tires they are showing signs of dry rot
2) at idle has a slight stumble/rough idle - not all the time but is something in need of attention - not sure what that could be, it drives great, no hesitation etc
3) steering wheel is off center when driving straight (assume is alignment or worse) - but it tracks straight down the road, no pulling etc.
Other concerns
4) we can't get the vin to work on any decode sites it comes up as 2001 model so assume the gray market is causing that ??
5) I can't tell for sure if it is really a 500 or a 380 - it does not have rear head rest, rear power seat or any heated seats. - on the 86 on I can tell a 420 from 560 by the dual air intake on the air cleaner for the 560, but on the pre 86 I think they all had single intake... any thought on how to tell this is a 500? Does not look like it has hydro suspension but could not tell for sure...

As always appreciate the forum's insight - you guys are the best!!!

Mark