Speedometer gear

[gman]

Need help identifying a part and whether or not there is a replacement available. It appears to be some type of gear between the speedometer cable and the transfer case. It is leaking bad, and I'm not sure what its called to inquire on a replacement. It is box shaped and on one end, the speedo cable goes in.......the other end has a small cable sticking out of it that goes in the transfer case. I've looked in the Assembly manual and a 72 GM parts catalog and can't figure out what its called. Any ideas? Can it be replaced or rebuilt? It is not leaking from the speedo cable end. Its leaking from the other end. Thanks for any help.