4 speed auto into '65 Barracuda?

Chrysler used 2.93 not 2.96 gears. But if you truly plan on keeping the car and driving it the overdrive might be worth the effort. You just have to have fabricating skills and a willingness to hack into the car to make it fit. Consider the fact that instead of 2800 rpms at 65 mph you would more likely be in the 1800 rpm range. That is not just a fuel economy savings that is also lower wear and tear on the engine due to lower operating rpm. You know that we are not going to be seeing $1.50 a gallon gas ever again so is a fuel economy improvement going to pay itself off in the long run. It all depends on number of miles put on the car.

Someone called it an "Oddball" transmission. That is far from accurate they were produced by the millions. If you see 2wd dodge truck with a 3.9 v6 in it from approx 1988 to 1996 it should have an A-500. If it has a 5.2 or 5.9 in that same year range it will have the A-518. It was used for some years after 1996, but it was computer controlled. They are plentiful, have common rebuild parts available. They did have some documented failure prone areas, but they are problems that can be addressed.