Does anyone know if you need to change the bellhousing when going from a C4 auto to a AOD transmission swap? Also, other than the rear Transmission mount, which I know has to be changed, is there anything else I need to change/purchase. Any info would be helpful.  

Cut and paste this thread:

http://www.mercurycougar.net/forums/showthread.php?t=23908&highlight=aod+swap

In part:

Started My AOD Install... long post!!

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While waiting for my AOD w/ wide gearset, 1-2-3/4 shift pattern, selected other 4RW70 guts, heavy duty frictions and nonlocking converter to be built and delivered, I've begun the R&R in the car. Got the C4 out, and started a test fit install of a lesser quality stock AOD. Things are tight, but look acceptable so far with a little messaging...

I pulled the flexplate off (just got the new 164 tooth 351W 28.8 unit today) the block and put the AOD in w/o the converter to check it out. I removed the passenger side Hedman long tube header to ease the install. Test fit this header back in w/o my double gaskets; it's close to the tranny but clears it! I used a cheater pipe and pulled both collectors away from the trans to pick up a little more clearance. When the gaskets are re-installed I'll pick up a tiny bit more space. I see why the trans cooler is recommended for this swap, though! The starter mated to the AOD is a tad further away from the engine, but clears the header also.

I had to cut an inch off my driveshaft yoke to accomodate the inch longer AOD, and interfaced the engine connector and the AOD connection for the neutral safety switch.

Right now, I'm hung up on adjusting the linkage. I've adjusted the AOD shift lever, but am off just a tad on detent positions between the floor shift and trans. If anyone has any insights on this, it would be appreciated. For now though, I'm looking for a spare stock C4 shift rod I can modify. So if anyone has one they can part with, let me know through a PM. I don't want to mess up the only one I have...

The TV cable will be the next thing I have to deal with. I'm thinking of just trying to modify the stock kickdown linkage cable, as the kickdown lever is in a good location, and moves proportional to throttle position. The other reason I'm considering this is because I have a 4100 autolite carb, not a Holley or Edelbrock. If any one has any feedback on this, it will be appreciated.

Right now would be a good time to pull out the limited slip unit out of my donor car, change the ratio, and install it. I'm thinking 3.50's, but I'm looking for someone who can recommend the right quality QUIET gears. I don't want a loud whiner gearset. Does someone know a source of polished quality gears for an 8 inch limited slip rear end?

Any insights on this install will be appreciated! Thanks!"
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There is alot more to it than that, but you should be able to get some good info from this site!

Steve