The smoke just came out of the FMX in my son’s 76 Ranchero…again.

18 months ago we lost second gear in this 1974 FMX that was in the car when we got it. It had been behind a stock 351M that was pretty tired. It failed just a few months after an engine rebuild with upgrades.


We really wanted some kind of overdrive transmission when the first one failed, but could find no affordable solution, so we got another FMX from a 68 Cougar XR-7 and had it rebuilt and had the selector switched to column shift.


With less than 5K miles on it since the rebuild (thanks to covid19), but 15 months later, all forward gears went out and reverse is slipping bad. Of course, it came with a 1 year warranty.

I suspect the 45 year old iron lump couldn’t handle the torque of our freshly rebuilt and upgraded 408 cubic inch engine.

This is the second FMX failure in 18 months. We are not going down that path again.

The biggest obstacle to overdrive was the big block bell housing pattern of the 335-series 351M/400 engine we have.

Ford never made an AOD for big blocks. For some reason, everybody seems to hate AOD’s and one local shop won’t touch them. Well, I found out AOD, AOD-E, and 4R70W’s are really all just souped up FMX’s in fancy new cases, which I am convinced by experience, can’t handle big block torque.

Many folks in various forums and face book groups said “put a C6 in it and be done!”, but that won’t get us one more upshift at 45 mph, or torque converter lockup. 

This beater needs to be a highway car, my son travels for work a lot. A bump in fuel mileage and range is needed.

Transmission adapters cost over $800 and then you still have to source a transmission.

After lots of research, I have a solution I am going to try.

I did find a kind of rare combination that I hope will provide the best solution: 1992-1996 Econoline based motor homes with 460 gas engines had E4OD transmissions in them that bolted up to the big block Ford bell pattern.

They are literally Super Duty strong and Ford had them behind big blocks and diesels in Super Duty trucks ,Econoline vans and RV chassis.

It should be an ideal match for our high-torque, low rpm engine.

It should never grow tired tossing around our light-as-a-feather 4300 lb Ranchero after hauling around 11,000 pounds of RV.

So I went looking for used motor homes and found one with only 42k miles for $500, but it was 200 miles away. 

I can’t put a 24 foot rv on a u-haul car hauler like an old Maverick…

I had no way to get it home.

Then I struck gold!

8 miles from my house, right next to a u-pull yard I have been to dozens of times, there is a motor home junkyard, tucked away down a dirt road I had always thought was a private drive way. Welcome to Florida!

They get $750 for complete big block engines with harness and $450 for a transmission with converter and harness.

Everything they have has ridiculously low miles, which is normal for RV’s.

I am getting the E40D out of this 1994 Fleetwood Flair 28 that has 22,000 miles on it. for $450 with the torque converter and trans harness.


I will have to cut out and raise the Ranchero’s transmission hump and weld in some sheet metal to clear the massive E4OD case.

I’ll have to find some place to get our drive shaft cut down and get the correct yoke.

I’ll need to move the trans crossmember, or maybe get a different one.

Our Ranchero has 2 trans crossmember locations. One for 6 cylinder and small blocks with C4 or FMX, and one farther back for 460 with C6. I wonder if the c6 mount location would work for the E4OD?

The E4OD is electronically controlled and I plan on using a $450 Quick2 trans controller from US Shift.

Stay tuned for Part 2!

Keep building!

See you on the road!