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i have a 1969 Xr7 cougar convertible shell i just picked up a 1969 351w that is being rebuilt with aftermarket heads and a mid range cam. my question is what would be the best transmission and rear-end combo for trips to L.A and Las vegas from the bay area ca. i plan on driving the car everyday and i want it to be reliable on the highway and street. i do not have a transmission yet so i wanted to know what would be the best one for the long trips. Fmx, C4,c6,4 speed,t5, i also heard i can use a AOD but from what year? all thoughts appreciated.
 

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AOD, not sure what year, but I'd say fox body Mustang would be a good bet.
 

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AOD for sure if you plan to drive it much on the highway and expect anything better than 15mpg. Oh, and if you go with an AOD, at least 3.25 gears, preferably 3.50 or 3.70. Even with 3.50 gears, you'll only be revving around 1800 at 60mph in overdrive. Compare that with a three-speed automatic and 3.00 gears turning close to 2300rpm at that same 60mph.

As for what year AOD, the newer the better since they got upgraded parts.

Or you can use a 4R70W and a stand-alone electronic trans controller. The benefit of a 4R70W is the lower First gear compared to an AOD. AOD has 2.40 First gear. 4R70W has 2.84 First gear. That doesn't look like much, but it is 18% lower! That makes 3.50 rear gears feel like 4.11s off the line (for quick acceleration), yet you have 3.50 gears in Drive and the equivalent of 2.45s in Overdrive for real economy.

Or you can create a Franken-trans hybrid and retrofit the 4R70Ws gearset into an AOD into what is known as a WR-AOD or Wide Ratio AOD and do away with the electronic transmission controls...

Decisions, decisions, decisions...
 
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