Trans oil is over filling the dana18 transfer case???

I have a stock 1967 cj5 with the v6 3 speed. The transfer case is leaking out of the speedometer cable that is higher then the fill plug. When I drain both the transmission and the transfer case then fill them both to there fill hole I drive it a few miles then check the levels. The transmission is low and the transfer case is overfull. Oil is getting into the tc then not getting back into the transmission. I called a local gear shop with a good rep and they said I would have to pull the transmission with the tc attached and bring it in so they can find the problem. Has anyone heard of such a problem?

Unfortunately I have not heard of this before but I am not well versed in transmissions. Just speaking purely out of speculation I would say it sounds like a clogged transfer tube of some sort. Again I know nothing about transmissions.

Thank for the reply. I am going to take the transmission out with the tc still attached and bring it to a gear shop. They said they will find the problem and replace anything in the two units that are warn. Going to be expensive but at least I will have a fresh power train with no more leak.

Can you let me know what they find. I am always interested in those types of things especially when I havent seen a problem before. You never know when it will raise its ugly head. Hopefully not on the Rubicon.