Well, I have to say once again that I posted some "not exactly true" statements previously.
We actually have one 5F model where I work. It is our "shop work horse". This is the same truck I mentioned in another thread some months back regarding a possible future engine swap out (which is still a possibility).
This truck has the 4Y engine in it.
The fuel system is all Impco.
VFF 30 filterlock, J Model vaporizer, CA 55 mixer.
I had not bothered to look for an idle up dashpot on it before I posted what I read in the manual I found. Yesterday at work I made a point to look closely at the shop horse and it DOES NOT have an idle up dashpot. Going back to look at the manual again I realized that this truck was built during the era where LPG was an afterthought at the OEM corporate level and all LPG units were considered as "aftermarket conversion". The manual's reference (and photos) to the idle up dashpot was for a gasoline carburetor, not a propane mixer. Sorry for the errata.
I will await some kind of response from someone before I add anything else to this thread as I have a feeling it is already moving to the dead letter folder.