FRPP is the standard though an auto you may need a new yoke...
It has a grain of truth. Shorter gears will result in the driveshaft spinning faster for a given speed. At high speeds, the shaft RPM may be high enough that the OE steel piece will begin to vibrate, a vibration that cannot be balanced-out. It can be pretty bad, enough to pound the bushing out of the tailshaft of the transmission... The fix is the AL driveshaft which has different mechanical characteristics that move this natural resonance to a higher RPM.
I've got 3.73s with the OE shaft and see no vibration but I also don't generally drive super-fast. With 4.10s or higher you might be needing one even for "regular" highway speeds.
he is right. it can only spin so fast.remember tire balancer only goes to 60-70. your drive shaft will spin much faster. being aluminum & lighter less nvh. it is also stronger than steel. ad wise for shafts any ford mag. will have one, between $200-1000.
Ive got the FRPP alum driveshaft and all I had my mechanic buddy do was swap the yokes , I got the driveshaft before my gears so I cant really say about the second part of the question.
Like the others have said, just get the FRPP Aluminum Driveshaft and swap the yokes. You can easily do it yourself if you know how U-Joints work.
The FRPP driveshaft is stronger, lighter, smoother, and looks a whole lot better under the car. I don't know if the price has gone up because of the increased price of aluminum, but when I got mine, it was too good to pass up.
Allowing your engine to rev more quickly
having 40% less rotational mass on the driveshaft
having a driveshaft balanced for higher speeds
easily worth the $250 bucks, in my opinion
Reducing unsprung weight is one of the most worthwhile mods you can do. (IE: lighter K-member, lighter driveshaft, flywheel, lighter wheels and tires are an easy one too - a stock motor doesn't need 11 inches of tire or wheel on the back)
I spent several hundred dollars on items that don't help with HP or suspension, but was money well spent to make the car safer: window switch for NOS, brake upgrades, HID lamps, Aluminum DS, stupid driveshaft safety loop. Sometimes it worth 100+ dollars to safeguard your current HP levels.