Interesting enough...I have been up old priests grade more times than I can count and honestly would not have a problem(from a power perspective) trying the run up it with my TT and F-150 Ecobeast. I am not sure I would be able to make some of the turns. That being said, I think it defies good sense to actually try Old Priests grade with a TT for two reasons: 1. I can only imagine how much fuel I would use going up it. I would prob just watch the gas gauge drop as the turbos sucked the fuel. 2. It seems to me to be stupid to put that much unnecessary wear and tear on a vehicle if you don't have too assuming you can actually make all the curves.
There is no way in heck I would even think about going down Old Priests grade with an F-150 and a TT.
I appreciate the feedback since we just recently got into the TT/RV thing. We have not made very many trips let alone on those kinds of grades. The advice is well taken.