2.8 is a very reasonable grade, most stuff should be able to handle that.
@Mountain Mover posted:I think you will find the Premier double stack cars a a little be taller than the autoracks. We use the double stacks to double check vertical clearances on the Paradise & Pacific.
You might be right, I have some, but they're buried somewhere in a pile of boxes. Hopefully, they're not more than 5.5".