I just bought a nice 1947 Wizard wd4. I need to know what and how to check for lower unit lube and what kind. Any help will be appreciated.

Look here for the "General Instructions and Parts List" for the WD-4S motor.
http://pub9.bravenet.com/forum/static/show.php?usernum=737212788&frmid=52&msgid=715480&cmd=show
They are the same instructions for the WD4 motor. WD-4S just has a recoil pull start. WD-4 has the loose rope starter pulley on top.

You want to read the section in the instructions that says "Lower Unit".

For lubricant use Lubriplate 105 motor assembly grease found at Napa or on the Web. Do not use regular grease, do not use modern outboard lower unit gear oil.

The brass plugs (#10 and #11 in diagram) more often than not are fused to the aluminum so it will probably be very tight or impossible to remove. If they will not come out without destroying them, you can disassemble the foot to clean out the old grease. It will probably be a good idea anyway since you will want to check out the condition of your water pump impeller. Pack the foot with the lubriplate grease before reassembly. The gears in the foot are the weak link in Wizard motors made by Mercury and are darn near impossible to find so take good care of them.
Have fun...you have one of the older motors.

Thank you, thank you, thank you. That is exactly what I needed. I have the WD4S model. another question is the color gold, can I get that color from homedepot or any automotive paint dealer?

Here is an old post on wizard gold paint color. There are different opinions as to what the original gold color was.
http://pub9.bravenet.com/forum/static/show.php?usernum=737212788&frmid=52&msgid=725551&cmd=show

Mercury Mark 20H Gold is as near as one can get to the old Wizard's paint.
You can buy it at http://www.nymarine.ca/

Lower Unit pictures that may help.
http://www.wizardoutboardforum.com/LowPics.html