What makes you think its worn out ?
I had my turbine apart recently and there really didnt appear to be anything to bugger up on the valve
It is spring loaded and I had just cleaned around it etc as best I could
Even if they arent available I think just a normal check valve from a plumbers would work in the short bit of hose
the old Ergo cab they had them as Hippo's Buffalo's and with sleeper cabs as well great big long cabs heaps of glass Kev the local IH Dealer gave me these pictures of Seddon and Atkinson trucks back in the early 80's
all Aussie trucks except maybe the second last one Tim I didnt know any one else called farmers cockys I always thought it was a Australian thing cow cockys cane cockys grain cockys and the list goes on I dont no why we give names to things in Australia as we never use them even citys towns rivers states the lot all have nick names we are funny buggers Paul