Diesel Vacuum Dashpot for the Transmission
This is the restrictor required to meter the proper HG's of vacuum to your transmission. Connects to the tranny switching valve on the injection pump. If your is leaking or not there anymore the transmission will not shift properly.
Another good reason to replace this is proper transmission shift function. A leaking or mission dashpot will cause hard shifting or erratic shifting.
Cost $15. ($5 online)
Again, same promises, but it can't be that cheap :)