Definitely a post-facelift car (1995+).

If the seller was reluctant to provide the VIN I would proceed very carefully. Also I don't believe the S-Guard was offered in the 420 variant. The 4.2l engine probably wouldn't have enough grunt to haul all that armor around. My guess is that the seller has mistaken the double glazed windows for bullet proof windows. It happens all the time.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles