Okay, this thread has been dead for a while but I am back working on this again. As I mentioned previously, I had replaced the vacuum advance, but the new one looks different from the old one. Stupid me, I threw away the old one assuming that the previous owner had used the wrong one. I have some pictures at the link below showing the two different vacuum advance units.
Vacuum Advance Pictures The one label VC 435 resembles the original that I removed and stupidly threw away. The VC 310 is similar to the one that I used as a replacement. The VC 310 type is what is commonly available from the usual suspects. You will note that these two have very different specifications.
Could it be that the Hydramatic version used a different vacuum advance? There are other things like this about the truck such as the automatic choke that was unique to the Hydramatic. Another question is if the VC 435 style advance unit is the correct one, would any unit that looks like this work?
