FMX to AOD Swap

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So, finally the Mustang is back on the road.

Maybe some of you noticed the update on my "idle pressure to high" thread. It turned out it was a stuck valve in the valve body. Once that was taken care of everything went smooth.

I'm gonna post both the effect of the swap and the parts we needed (and did not need). The latter is important because the Internet is full of "you need this" and "you don't need that" and in the end we were none the wiser.

Before we start, let me remind you some basics on my car: It has a 351W from Ford Racing, the stock FMX and 8 inch rear axle.

All the info below was true for MY car. Don't blame me if it turns out to be different on yours. :)

The suppliers listed below are the ones I bought from. There are others out there, you may wanna check with them. The links are for better reference.

Before and after:

It is amazing how much of a difference it makes. The first three gears are the same in ratio on the AOD and the FMX, so not much difference there. But as soon as the OD kicks in it's a different world. No engine noise, no exhaust noise, only the wind noise on the convertible top.

One ting to remember is your rear axle ratio. Mine is a 3,0:1 which is a little low for this setup.

At 35 mph You will have a little under 900 rpm, which is actually idling rpm.

But, on the other hand, it is cool for freeway cruises.

Remember, I am in Europe and can have fun on German autobahns. :)

When going 110 mph, rpm is 3000!

At 65 mph it is 1700 rpm instead of the previous 2500 rpm with the FMX.

I will change the rear axle ratio to a much shorter one, probably 3,8:1 after I got the car on the dyno. Then I will know at what rpm the engine delivers best and I will match the rear ratio accordingly.

Oh, by the way, the positions of the stock shifter lever can be made to match precisely. It takes a little setup but no modification is necessary.

Parts I needed:

Lokar KD2AODHT - Lokar Hi-Tech Kickdown Kits

Lokar SRK-4000 - Lokar Throttle Cable Brackets

Lokar ATA-1000 - Lokar Ford AOD Selector Shaft and Arms

We ended up making a custom part and did not use this one. Reason is the hole in it was too small to accept the original shifter rod.

It was also pretty hard to align the shifter positions with this one. You may wanna try the one with only a slot and no hole, maybe that one will work better but I can't say for sure. Link:

Ford Racing M-4841-B - Ford Racing Transmission Yokes

My FMX had 32 spline and required this new yoke. Problem is that it is a 1330 yoke and the driveshaft had 1310 ones, so we also needed:

Ford Racing M-4635-A - Ford Racing U-Joint Conversion Kits




Inspection plate (for bottom of bellhousing)

New AOD conversion crossmember

(you can modify the existing FMX crossmember to fit but this is a direct replacement and much sturdier than the flimsy stock crossmember. Plus I think it is not a good idea to cut parts off of structural parts. By the way Summit have their own version of this part but as I ordered other parts from PATC I got this from them too.)

AOD conversion trans mount.

Things we did NOT need:

OD NEUTRAL SAFETY SWITCH PIGTAIL as that switch is built into the shifter on a 72 Mustang.

New speedo gear (the stock one fit and works precisely)

Engine block off plate. The original one from the FMX worked fine, only the inspection plate at the bottom did not fit and needed the aforementioned replacement.

New starter. Although many posts on the web say you need one, we did not. The stock one fit perfectly.

New flexplate. Stock one worked fine.

New shifter and new shifter rod (and rooster comb or whatever shifter related parts). The stock ones work perfectly and the positions of the shifter match.


We needed to shorten the drive shaft for about 3/4 inches and the transmission cooling line has to be reworked. The front one will fit but the rear one will need to be shortened.

Here are a few pictures:

First, the new transmission crossmember (and mount). Sorry, it's a pretty crappy cell phone pic. you can see how this is much better than the original flimsy crossmember used by Ford. This looks like it even adds rigidity to the seat platform area of the chassis compared to the original one.

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Here's a pic of the cooling lines before they were shortened. You can see the in and outlets on the trans and how one line will fit and the other one goes all the way to the rear of the trans body and will need to be shortened.

View attachment 19316

Here's the Lokar Selector Shaft. Compare the diameter of the hole to the rod and you see that it won't fit.

View attachment 19317

This is the custom made part that replaces the Lokar thingy.

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