I am in the process of building my 64 c20 and have decided to put a nv4500 transmission in it. I have found one but i don't really know what to look out for. I know what one looks like. The one i have found has the covers off and looks dry of oil. so the gears are in full view. it is a reasonable price. when i go to look at it, what should i look for? i will attach the covers and rotate it through each of the gears. should i spray some wd40 on things just in case? what issues are common with this transmission? any thought and help we be greatly appreciated.