Need help with Ignition Switch and Cylinder!

[mgeez]

Specs:
51 Chevy truck 3600
12 volt
Seperate push button start.
Only want the keyed cylinder to activate the ignition circuit.

Has anyone done any troubleshooting with the ignition switch / cylinder.
I think I have 2 problems.
I inserted the cylinder into the switch. There appears to be 3 positions I can turn the key to: Acc, off, and on, in clockwise order. I expected the key to pull out only in the off position only. It pulls out in the acc and the off position, but does stay in the cylinder in what I believe to be the "on" position.
In addition, I have no continuity whatsoever in the on position, but do have continuity in the off and acc position. It does not make sense to me that I would be able to pull the key out while the engine is running. I took the switch apart and all looks real good.
Any suggestions or education as to the correct operation of this would be appreciated.

[mgeez]

Problem Solved!
After 2 hours of scouring google images, I found I have a 50's Fleetline ign switch, which is slightly different from the truck switches. The Fleetline also uses a different ign cylinder. I was trying to make a new truck ign cylinder work in a Fleetline switch housing.