Thanks for your reply. Yes, that's what I was thinking - that there is enough corrosion in that area and on the shaft of the broken bolt to hold things in place. I didn't mention it in the original post but I also reattached the head of the broken bolt to the shaft with some J-B Weld - making sure to put on enough that it spilled under the washer and head of the bolt onto the solenoid base. Between that and the corrosion I am hoping that it will stay put. But one day that overdrive solenoid may have to be replaced. I'm afraid that's when the real fun will start! Removing the transmission may then be the only option. :(