I have a 1974 f250 that I just swapped the dash out of. When I put the new dash in and turned the key it starts in the on position instead of the start position. It wouldn't be a big deal except that the starter won't turn off. I tried 2 switches and it didn't fix it and it worked fine before I took the dash oh thanks for any help.

 

Sounds like welded contacts internally in the passenger inner fenderwell mounted starter solenoid?

 

Given that it happened when you removed the dash, I'm wondering if you messed with the wiring to the ignition switch?

Could also be the wires for the "I" and "S" terminals crossed at the starter solenoid.

 

welcome to the forum njmeyers, what part of il do you hail from and do you have any pics of your truck to share?