I tried to get the crank assemblies for my 91 several years ago. Sent Jackson a picture and Airstream claimed they NEVER used such a thing and I must have installed them.
If the gear is stripped, like mine were, you can drill the rivets out and rotate the gear 180 degrees. The crank only uses less than half of the travel of the gear. Just make sure you lub the gear before reassembly and you will most likely get as much or more than the original life out of the rebuild.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles