Transmission slipping out of gear

SAmato

Hello, I recently purchased 1947 Hudson Truck with Twin H 308 with overdrive. I just signed up today to this forum. I always appreciated Hudson vehicles. when I was young my uncle had a '53 Hornet and I thought that it was such a cool car; fast and it glided out on the road and looked bitchen. 
When I purchased the '47 truck the previous owner replaced the clutch oil with the correct Hudsonite oil and said that I would have to pump the clutch a few times in order for the new oil to work in and it would take a little bit to engage properly and that after a while it would be fine...well its not getting any better. I can get it into gear by rolling it forward in 3rd and then throw it in 1st. After that going through the gears the transmission operates fine except when the rpms are lowered while in gear the transmission slips out of gear. at this point if I disengage the clutch and reengage while in gear and then reestablish rpms under load the transmission will be fine until the same process happens again. Also in third trying to engage the overdrive it does not want to engage. The overdrive seems to be working electronically I can hear the actuation but just grinds and not engaging fully. I did read a past post on just this issue and I will visual inspect and verify if the travel of the cable is adequate.
So that being said am I looking at a clutch adjustment here if so any tips on that ? or am I looking @ transmission problem ?

Also while I am @ it 2 side questions:
1- The dip stick seems to be too long it does not seat properly.. simply cut back? and if so to what length. how far from the bottom of the pan?
2-Hood spring stay. I have looked on-line for two new replacement hood spring stays and I can locate. I am currently using a PVC pipe holding up the hood  
Thanks for any advice 
Steve,

SAmato

Thanks Ken,
It slips out of all gears. I'll hoist up and take a look @ the cross member.