Just for reference, my car is a all steel 64 Galaxie. Street driven. My next power plant has to travel from here to there occasionally but I sling it down a 1/4 mile now & then too.

 

I have one of the Ford 572 crate motors going in a 1970 Cougar I was told that no stock trans would be reliable,as I have a built AOD but Ford tech said that I might get 2 or 3 hits out of it. So I now have a Transmission Depot Custom with a overdrive that doesn’t lock up as they said the shaft would not hold a lock up Wild engine if we can ever get it installed, we have so far put a A arm suspension plus cut the firewall and many more changes. I have a Currie 9 in with 3.70 gears and 33 spline axels. I will add more if or when LOL we get it going. Wish me luck.

 

An AOD, even with an aftermarket hardened inner shaft, (two-piece input shaft is needed for converter lockup) is limited to ~550 lb/ft torque. A one-piece shaft in an AOD that eliminates converter lockup in D and OD is good for ~ 700lb/ft. A 4R70W is limited to ~700 lb/ft and has electronically controlled converter lockup, and a E4OD/4R100 are good for 1000 lb/ft torque, but there's lots of parasitic power losses with either the C-6 or E4OD.

I have a custom wide-ratio AOD in my '89 Crown Vic behind a dyno-verified 504hp/470tq 395W. I was running a ~2400 converter previously, and it was barking the drag radials at the 5300rpm shifts with 3.55 gears. My 60' times were slug-slow at right around 2.0 seconds (best was 1.95). With the new upgraded 610+hp/495tq motor, I also opted for a 3200 converter (still with lockup) to lessen the driveline shock at the shifts. I'm right at the ragged edge of the inner shaft's capability.. Remember, it is torque limited, not horsepower...

 

What any component will take depends on if you hook up or not. If you're just spinning the tires, there's virtually no load and even stock parts will last a long time. My 8" I had in the back of my Mach 1 lasted a long time behind the nitrous'd 351C that was in it previously before I put slicks on it. Then it went boom real quick like.

 

8" rear? That was only used in Mustnags behind six-bangers and 302s. 351-2V and up got 9". I collect '71-73 Cougars, and have had close to 20 over the past 48 years. My first 'official' car was a '72, 351C-2V/FMX/2.75 9". I still have two - both are '73 Q-code 351C-4V/C-6/3L25s... although now they have 3L70 and 3L91 gears.

My one buddy is running his '71 Mach 1's original FMX trans (was 351C-2V/FMX/3.00 9" stock) now behind a 545" stroked 460, utilizing a bellhousing from my old 351M/FMX '78 Country Squire. FMX has cast iron case and center support bearing. No other Ford 3-speed automatic can boast that. The AOD internals are based on FMX, larger frictions than C-4, and also has a center support bearing. The weak link of the AOD is that two-piece input shaft (inner shaft).

 

Tried to attach a video of my FP 572 Crate engine in my boat for you to hear what it sounds like. Could not get it to work 🙁
R,
HAP