The body is steel with the exception of any ground effects the car might
have. Two vehicles that the body is flexing and cracking on? What kind of
re\oads do you drive on?

nospam

I've seen it on unibody construction but not until about 200k miles.

Has someone been playing Dukes Of Hazzard with your car?

Perhaps the car was banged up before you purchased it and were not
informed about it.

=========
Harryface      
=========
 
1991 Pontiac Bonneville LE
3800 V6 ( C ), Black/Slate Grey
_~_~_~_~279, 000 miles_~_~_          

~_~_~_~_U.S.A._~_~_~_~_~_

   What you have is a stress crack. Which means your car has seen, and  is
seeing Extreme Flex.

   Stress Cracks are common on all 82 to 92 F-bodies (Camaro, Firebird,
Trans Am) where the B-pillar meets the roof. F-body cars Flex, and Twist
under normal driving conditions. They are the Extreme in GM flex-I-fliers.
All  GM Uni-body cars will flex, trust me, owning a lift proves this. Lift a
GM Uni-body car by the factory lift points, not the emergency jacking
points, and  it's a 50/50 gamble  if the doors will open.

   Yet for a Grand Am to exhibit such flex on the road as to crack the
A-Pillar, you have a serious issue. The Pillars are some of the strongest
parts of the body. They have to be able to hold the weight of the car from
crushing the roof in, during low speed roll overs. When  you think about the
weight of a car, compared to the size of the pillars, and the fact that they
will hold. You get an idea of how ridged they are. On that note, if the
pillar keeps cracking, you will have a cracked, if  not crunched windshield.

   You car should be inspected right away. Not by a dealer, but by a body
shop that specializes in frame collision work. Don't give them any stories,
don't mention any  thing about suing the manufacture, ect ect. Just get an
un-biased report of the cause, and how extensive it is.

   As for the truck you had, to lose 1 back glass meant  a serious problem.
To lose 6, and not have the dimensions checked, was moronic on someone's
part at the service center. Truck cab's don't flex. Lose two body mounts,
and they don't flex. They shake. They do not normally even distort around
the remaining mounts. Only under  extreme duress do they, normally by then
the driver would be dead.

   They will buckle inwards from impacts. So unless someone had dropped
enough of a load on the roof of the truck to deform it, pushed in on the car
sides, and the bed wall. The window should not have popped out unless the
panels were not joined in alignment and  measurements. This would have also
shown in the door gaps, and the  fender to door gaps.

Charles