Here is and excellent article on restoring one http://www.speedprint.com/deves50/heaterrestore.php. You are correct on the pull cable/knob it attaches next to the fan switch you have under the left side of the dash. Best explanation on set-up is in the Accessory Installation manuals they show that in detail I am sure Tim will see this and he can add those links. Here are a couple pictures to help show the set-up as well. After reading your post closer I will add that I think the factory heaters add a ton of character to the truck and once rebuilt they are a nice addition. If your motor is original 6-volt it will probably just have one hot lead coming out of it most of the 12-volt replacements have 2-leads one + one -. Your heater would have cost the owner around $55 bucks back then which was a substantial outlay at that time. I say restore it and enjoy it!

http://good-times.webshots.com/photo/2738738300102454676GDFfat
http://good-times.webshots.com/photo/2282825960102454676njXUMq

Last edited by Brad Allen; 11/04/2009 12:23 AM.