I know the NCRS shipping reports are not listed for Monte Carlos but run the Monte Carlos Vin# through the NCRS shipping system on the car. As you know Monte Carlos were built at certain plants on the same assembly lines and are on shipping manifests with Chevelles. I had a Flint Built 1970 Monte Carlo SS454 (goodluck finding a build sheet on a flint car) that I ran the shipping report on the car using the cars VIN# just listed the make as a 1970 Chevelle because Monte Carlo are not an option. I got the shipping report back saying 1970 Chevelle (really 1970 Monte Carlo vin# 138570Fxxxxxx) was shipped to the exact dealer that I had thought. My shipping report said the exact production date and dealer and vin# of my Monte Carlo its just listed it as a 70 chevelle.

Why is it only a problem on some carlines? Is it an axle design issue or something else?

Usually it has to do with the interior volume. Vehicles like vans or Suburbans are particularly sensitive to all kinds of disturbances, since the body cavity can respond like a drum. An axle that would be ok in one vehicle would be "bad" in one of those.

The other consideration is if the "noise transmission path" is through the structure or is airborne in nature. Normally it finds its way into the vehicle through the rear suspension (you can actually detach the rear suspension and run the vehicle on a chassis roll dynamometer to verify the noise goes away). That is what was unique about the GMT400 project is that the noise would radiate off the drive shaft and was airborne - if you were standing outside the vehicle you could hear the axle whine as the truck drove by...

K

The 67 Caprices got that. Possibly other year Caprices as well where the other fullsize models did not.

I've never seen jacking instruction decals in that location.
I'm certain I haven't seen them all, but I've seen quite a few first gen Montes. lol
Is that a common location for Flint cars? Chevelle too?

NONE of the survivor Flint (Chevelles) that I have in my files have the jacking instructions in that location. The silver Monte in front of it on the line has it in the same location as well.

I had a 09B (Sept 69) Flint Build 1970 Monte Carlo that the jacking instructions were in the exact location as in these assembly line pictures. I then had another 02B (February 70) Flint built Monte Carlo that the jacking instructions were on the lower portion of the trunk to the drivers side of the center divide. Both very original cars original decals. I have seen more Flint Cars with the 2nd style which leads me to believe there was a Jack Decal location change from the start of production to early in the model year. I also noticed that if the car was to have a POSI decal it remained in the same lower driver side next to the center trunk divider regardless of what jack instruction location the car had. But if it was a later POSI car it pushed the 2nd location Jack Decal to the passenger side lower center next to trunk divide.

My ss454 was silver with black top and black inter. Sorry I did not keep any info on them. Never though it would be important back then. Cleaned out the glove box on two 69 z28's and threw the pop and paperwork in the trash. Soooo dumb back then..