Here's an update.
Following the trip to Elkmont, the AC compressor blew up. At least it happened before we went out west! Our mechanic repaired and we had 2 weeks to drive the Ex and test the repair. Since all looked good, we gave ourselves the greenlight.
About 2 weeks ago we headed west. Long story short, back home now having logged over 5000 miles. The odometer now shows about 135K. We drove through some desolate areas such as 89A into North Rim, and across WY on US 26. I really held my breath on those sections, and the Ex toiled on...
Some snippets for conversation: Route 89A into North Rim from the east is a real bear! The grade and switchbacks (with a strong wind from the west, and temps around 95F) were some of the worst we've encountered, I had to down shift into L1 and the v10 was screaming at 4000 RPM to get up that sucker! BTW the North Rim was beautiful.
Heading north out of Salt Lake City on I15 was a rough go, the temp was 100F with a very strong head wind meaning I had the pedal mashed for hours turning almost 3000 RPM to keep the engine in the torque curve. We saw 2 Class A's that bit the dust in those conditions, poor folks!
FWIW, the V10 with the right tranny is probably a capable engine, but the 4R100, she's a dog. For example, when I hit a mountain grade with a headwind I'd get her up to 75 MPH trying to keep the RPM's over 3000 (in "D" with OD off), but the rig quickly would lose speed on the climb and I'd have to downshift to L2 and creep up the grade at 55 MPH, 3000 RPM. BTW, the gearing is 3.73 in the differentials.
Too bad Ford didn't use the Torqshift on the 2005 model V10's (I understand the 6.0 diesels were so equipped), just a thought.
Just a few local trips planned for the rest of the year, and off we go in September to Hershey motorhome shopping, again!