Welcome to the forum. Nice sounding little truck! We're all a sucker for a good picture, you should get around to posting some.
What do you mean by oil at the rear of the head? Seepage leaking down the backside of the motor? Moisture on the valve cover? Pull the valve cover and see it in the head? Fill us in on the details and we'll see what advice we can give ya.
Your truck is the same Year/Make/Model as bradMPH's... He's completely rebuilt and revived his truck. You should check out his thread. its a fun read.
http://www.mightyram50.net/vbulletin...ebuild-Replace