Yuuup - its the old Park to Reverse issue common on F250's with a Cruise O Matic

When Ole Blue is sitting in Park, it frequently will slip into reverse. Happens when starting, when sitting at a stop light, when idling in the garage during a tune up. When Uncle Ken was having Ole Blue worked on in the 90's the mechanic wasn't aware of the issue and actually tore off the driver side door when he left the door open while working up front and the transmission slipped into reverse, idled across the yard (in reverse) and hit a tree or something bending the drivers door towards the front of the truck -- AAACCCKKK. (They found a replacement door and painted it to match Ole Blue's Marlin/Wimbledon colors - it still doesn't fit very well - maybe was off a '64 or something).

Anyway, I was reading threads on the FTE forum the other day and saw where Bill the retired Ford Parts Manager responded to a reader with the following info:

"What you're referring to...is not a defect, it's caused by human error. It's a somewhat common occurrence that affects all 1961/96 trucks with A/T.

People put the shift lever into Park before setting the hand brake, causing the truck to roll...just enough...that the parking pawl inside the trans locks up tight.

Now the shift lever has to be YANKED out of Park and before too long, the detent aka shift gate that the tab on the shift lever locks into between Park & Reverse...snaps off.

C5TZ-7A216-A ... Detent-bolts to bottom of upper steering column flange ~ 1965/66 F100/250 240/300 C4 & 352 MX C-O-M / Obsolete

No Ford Dealer or obsolete parts vendor has any. "

I will try to find and replace this piece while swapping out the turn signal switch ....

Uh Ohhhhhhh

C5TZ-7A216-A Is not available, however, we found this thread on FTE: 

https://www.ford-trucks.com/forums/1091088-update-on-auto-shift-detent-my-repair-worked-too.html 

(Use a detent off a /73 bronco)  

Another story: 

https://www.ford-trucks.com/forums/1316668-shift-detent.html 

(Make sure the detent is the issue - this guys root cause was his shift lever) 

I took off the steering wheel and immediately saw that the 2 'ears' were broken off the turn signal switch - ordered that up from one of the current replacement parts stores. Following the advice of users at the FTE forums I ordered the complete part with wires, as all recommendations say replace the complete switch NOT just try to replace the white plastic thing as this almost never really fixes the problem of turn signals not working correctly.  

Decided to take a look at the detent while prepping for new turn signal switch, I unscrewed the three retaining screws and pulled back the turn signal switch, then removed the two center shifter retaining nuts and lifted out the shift mechanism. Turning over the shift mechanism, the detent looked great - no cracks or deformities.  

Taking a closer look at the Shift lever, the end looked a little different then what was shared on the FTE forums. 

I saw a little piece of steel laying next to the end of the shift lever (see 1 below) and a rough edged on the end of the shift lever - the tab had broken off !! (see 2 below)  

ROOT CAUSE OF OLE BLUE shifting into reverse was NOT the detent at all - it was a broken lock tab on the shift lever!