Cheese and rice! Who knew trying to get these would be such a nightmare? I've called no less than 12 parts places (including Ford themselves) and it seems these two units are rare or some such shiznit. Not only do they seem hard to find but the pricing is all over the board. I finally settled on ordering from Stock Wise Auto via Amazon. They had the best price as well as earliest availability.
The Dorman 692-072 sending unit for my 18 gallon tank was $57.71 and the Dorman 692-115 for the 22 gallon tank was $47.37. I didn't expedite shipping because with the Monday holiday it really didn't make much sense. This sure beats the prices of $103.79 & $99.99 that I was quoted by both NAPA and PAPA. Other places couldn't even get the parts and Ford tried to make me purchase fuel pumps with each sending unit (which since the van goes I obviously don't need).
I also called the folks at Stock Wise to make sure I was ordering the correct parts. The customer service dude was extremely friendly and helpful. I'll definitely order from them again if I need to.