I don't know if you are still looking for K-MAC sway bars for your van?
I have a pair of mint condition NOS that have been sitting in my bedroom cupboard since 1984 and still as new.
I bought a brand new 1976 yellow HX sandman from Hillsdons Holden in Parramatta back then and fitted it with a K-MAC rear sway bar. A few years later my dad bought a new 1979 HZ SLE Statesman which he left me before he died.
I bought these to fit it then but they were never use as I sold the car.
Daryl