I've perused all the parts manuals and can't find a schematic break-down of the hydraulic system. My D4 7U s/n 2048 is leaking at the top right hand side of the tank valve control where it engages the blade lift cylinders as well as back at where I'd call it a diverter out the top underneath the moveable handle. So are there seals there to replace and any part number recommendations if so would be greatly appreciated. Just thought of this and because I don't have anything to hook up to at the diverter box, what about eliminating it entirely??
Thanks in advance, Dennis 

The hydraulic parts manual is available in the members library or on eBay. Seals are still available and are readily found on eBay.

The diverter seals are all just orings, to replace the seal on the main unit you'll have to pull the front of the pump off.

Thanks a lot. You have been an inspiration to me and i've watched your videos multiple times, thanks again!!

you could simply replace it with a solid connector block.

it should be a type 44 hydraulic unit the seals for the fittings are available any hydrualics shop. as the fitting are sae code 61

Without a picture no idea of what brand we are dealing with. Cat was only getting started making their own hydraulics, so there are many other brands out there.

the pumps cat supplied where made by sperry-vickers anyway. which is now part of eaton fluid power. but yes it could have anything on it.

The leak on the diverter as as simple as changing an o ring. The leak on the shaft coming out of the hydraulic tank is probably more to do with wear on the shaft and bushings, which a new seal will probably curb for only a short while.

Yeah without pictures of exactly what you are talking about like Ray54 said. 
Is this what you’re referring to?
Here are pictures of how the steel hydraulic tubes are attached on a #44 power unit. They seal with a simple “O” ring in the groove on the hydraulic unit and or diverter valve and the machined surface of the mating tube.  The hose adapters have  the same “O” ring groove. 
 

if its the control shaft leaking you can get new bushes from the dealer not cheap though there a simple brass bush. the seal is also available.