Ford Repair: AOD Trans. OD Problem, overdrive band, aode

Question
Thanks Steve
My son has a 1991 Mercury Grand Marguis LS,
With the Car in Over/drive, The Trans/shifts
good up/to about 40 MPH, Then drops out,like
it was shift in neutral. The car runs/shifts in
1,2,3 great when in drive. I now know it's a
AOd or AODe Trans. It's a High milage car 156,00.. I'm thinking it's time/replacment.
I would like to be sure, can something else
cause this problem, then a problem in the
trans. I'm thinking first filter/oil change
first/ before changing the trans. Thanks for
any help.
Clyde  

Answer
Clyde-

  I think it's an AOD.  It's hard to be sure since Mercurys and Lincolns got some technology earlier than regular Fords...but the problem sounds like a bad overdrive band which wasn't so much of a problem with the AODEs.  If that's the case, you can either replace the OD band and hope nothing else in the transmission goes or just replace it.  Rebuilt AODs aren't too expensive these days, but they're by no means cheap.  I'd sit down and plan out a reasonable expectation of how long you'll keep the car and how much mileage you want out of it before dropping that kind of money on a rebuild.  Hope this helps.

Steve