Not surprising that neither Fox nor Push will work on an older shock. The newer stuff is way better in comparison.

Nuther option I'd recommend is Cane Creek. They have a trade in program for their Cloud Nine shocks which knocks off a $100 or so. Plus, they can custom make a shock for you, just call them up and provide the specs of your current shock. I have a Cloud Nine on my NRS and it was a vast improvement from the stock SID.

Good luck in getting your dually back to full working order.