Frank, thank you for the reply on the part number.
Eric - you really hit it on the head! I had been on the phone with 4 State Trucking out of Joplin, MO, but they couldn't verify all the dimensions. There were two tanks that looked close, only one in stock, but wasn't willing to order if I didn't know for sure which one. We found a small truck repair shop, ARS Truck & Equipment, in Ft. Mohave just north of Needles that was able to help us verify the part number. Yep, they called around and in the end it was the FORD parts dealer that had the exact replacement part and number, F6HZ-8A080-B (replacement part number for F5HT-8A080-HA). Will gladly pay the upcharge for ARS to source this for us as we will save a ton on O/N shipping as it will be here tomorrow morning with the "regular" deliveries. Otherwise we were looking at over $200 for 4 State to send it out 2nd day air to Needles! Also found that the 4 State part was not the correct fit anyway, perhaps Vander Haag's online had one that would work but aftermarket manufactured by Automann. All had the same shipping problem to Needles.
Of course, we started leaking a few hundred miles ago, tried a few patch jobs to try to get the our destination in Mesa, AZ, but by January 31, over the Tehachapi Pass and thru the Mohave desert, we knew we just needed to stay put and get a new tank.
The long holiday weekend was not the best timing, but lucky to have friends in Needles and a big shout out to the Elks Lodge here for having some nice RV hookups for us! The answer in the end was to go directly to Ford, but I thought they no longer manufactured a replacement so I didn't even think of doing that.
Thank you all for the quick help. I'll also look at replacing that cap as well, once we get somewhere to have them check the coolant system! Happy travels.