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Just bought 69 Cougar 351W - 4V XR-7. The FMX is shot, should I rebuild the FMX or swap to C-6? I don't know what the swap would entail. I plan on building the 351w to 350-450hp. Need a reliable transmission to handle that power. Would like to hear from people who have done the swap or swapped in an AOD transmission.
 

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Any of the above are good options....that FMX can be built if you want, but the C-6 is a more likely suspect if you have one handy. I went with an AOD after I shelled out my FMX, mainly because I wanted to get away from the track and back on the street. It was a pretty good choice overall. There are a lot of options availabe in the AOD world now that make it a very attractive alternative. They can be built to handle anything you throw at them for not to much more than the old stuff, and you get the benefit of hearing yourself think going down the road. I get pretty decent milage - about 18ish
 

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Does an AOD require modifications to install? Different Crossmember, drill new holes, Replace Cooler etc...????
 

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The swap requires a different or modified crossmember, different or modified driveshaft, new kickdown cable and different speedometer gear. Other than those things, it's a bolt on using the existing FMX flexplate. If you stay away from the electronic versions, it's a real easy swap. If you prefer the later electronic versions, you'll have some wiring to straighten out.
 

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Does an AOD require modifications to install? Different Crossmember, drill new holes, Replace Cooler etc...????
Yes as stated above. The biggest impediment is the TV cable that has to be properly adjusted or get a valve body with the TV modified.

I highly recommend talking to Jay @ www.BroaderPerformance.com

The FMX is still a good trans to keep in the car. I have run FMX, C6, AOD in my car and currently have a C6 in it. Is it worth it for the average street car? No.
 

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I would go with the AOD, I did my buddies fairlane, it was not bad, a new crossmember, new yoke for driveshaft, fab cooling lines. He later had a 456 gear put in rearend, excellent take off power and could still go on freeway.
 

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Does an AOD require modifications to install? Different Crossmember, drill new holes, Replace Cooler etc...????
The FMX is a good transmission .You can often find good used one cheap because they removed it for an AOD.

I installed an AOD about 15 years ago in my 70 cougar. It had an FMX. You can use your existing drive shaft if you use the AOD yoke. The big AOD fluid pan interferes with the cross member. Cut 1/3 of the cross member away so it will not touch the pan. The speedo cable plugs right in however a different cable end gear may be required as some AODs have 7 teeth and some have 8 teeth on the output shaft.

The throttle feed back cable kit that is available commercially will make install and set up of the cable much easier than what I had to do.

I had to ding the H pipe to clear the previously mentioned large fluid pan.

When your AOD hits 4th gear, it will continually put a smile on your face.

John
 

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For a street car, any of the OD transmissions is AWESOME. My T5 has the .63 5th gear, and at 70 mph with a 3.50 gear, I am only turning about 1800 RPM's. I hav eto down shift to pass anything on the interstate, as I'm not even on cam at that rate!
 
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