I am by no means a tranny expert, but Ive worked on several different Dodge and GM trannys, so heres a shot....
This all assumes the tranny was built properly. When a tranny sits up, all its rubber seals can dry out, and the moving parts can gum up from not being used. A PG is a fairly simple tranny, not as much to go wrong with 2 forward gears. Did you fill the converter with fluid before you installed it? Is this converter new?
If you are hearing a little whine, it is most likely the converter or front pump. The tranny should produce some forward or reverse motion even if the valve body, linkage, or clutch packs were stuck. It is also possible that the clutch pack seals are dried out. This allows fluid to leak around the clutch pack and can prevent clutch engagement.
Does a PG have a pressure test port? You could test the integrity of the converter and front pump with some line pressure tests. You could also pull the pan and look at the valve body before you remove tranny.
good luck
chip
