Hello I just purchased a new distributor for my 78 e150 with the 4.9 litter engine. The problem I'm having is I can't take off the Hexagon shaped shaft from the old one to put it on the new one. Is there a special tool tool remove it. It has a little thing that looks like a Ellen wrench would work on it but, when you use the Ellen wrench on it it keeps spinning. Any body's help would appreciated.

 

Pictures would help a lot..

 

I'm not that familiar with the late 70's engines, but there shouldn't be anything retaining the oil pump drive shaft (that's the hex shaft) to the distributor. It's possible it's stuck in there after all these years of service.

The hex shaft should only be inserted about 1" or so into the distributor (if even that much), so examine that area of the distributor shaft - do you see any set screws? If not, there's nothing retaining it. Spray some PB Blaster or equivalent around the hex shaft where it meets the distributor - if you can hold the distributor upside down that will help it penetrate.

Wait a few minutes, then take a small hammer and LIGHTLY TAP the hex shaft side to side near the base of the distribtor. It won't take much - all you're looking to do is break it loose. Try tapping 3 to 4 times on opposite sides of the hex shaft and then pulling on it to remove - repeat as needed until it's out.

Only do this if you've confirmed there's no set screws. As nsxman said - pictures will help us help you.