Just purchased an axle assembly from http://colawrvsalvage.com
Called 30 different places today. 25 aren't around anymore. Those that I could chat with didnt have the exact model. Colaw knew enough about these axles to find an equivalent. I think most P series chassis axles would work but couldn't confirm.
$1450 shipped from MO to Chicago. Hoping install won't be too bad and might be able to sell the differential to help offset the costs.
Found others on c-list for much less but they came from a F-250 and wasn't confident it was the exact same.
Fingers still crossed that it bolts in!