How to: - M50D-R1 to M5OD-R1HD Swap | Ford Explorer Forums - Serious Explorations

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How to: M50D-R1 to M5OD-R1HD Swap

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Well-Known Member
October 10, 2006
Reaction score
City, State
Wall Township, New Jersey
Year, Model & Trim Level
1991 EB 4dr
Hey guys,

A little less than a year ago I converted the 1991 Ex to Manual, ditching the old A4LD. The U join-t had spit a cap doing about 70 mph, and the jolt of the trunnion hitting the driveshaft cracked the back of the A4LD case/ 4x4 housing exstension. At this point I swapped in an M5OD with about 160k on it. Shifted pretty smooth in the donor it came out of.

Within the following months I could not get it to up shift perfectly into 3rd. I would get a grind if I wasn't careful, and I had to limp the damn thing most of the time between that 2-3 shift. I figured replacing the shifter bushings would mitigate the problem, and it did in fact help. It got to maybe 10-20% of the time clipping a gear as it went in, but this still wasn't satisfying me. To my dismay, driving home the other day it seemed fourth did not want to go in first try anymore, and at this point I began looking around for a real solution.

Doing a little research, I'd narrowed the problem down to most likely being either worn syncros, or a worn shift fork. Pricing out the parts, it seemed the syncro and bearing kit came to about $200, and the shift fork could be had for about $30. Not bad I guess, but curious to see what a replacement tranny would cost me, I ventured over to

The deal I found there baffled me - $550 for a BRAND NEW M5OD from a 2003 Ranger, and after calling the Ford dealer to cross-reference the model number, I discovered this was an HD unit. The benefits of the HD over the normal R1 seem to be trivial, but from what I have came across in my reading, I have determined there to be two pros to installing the HD unit.

1) The HD M5OD has a bellhousing that will bolt to your good old OHV, yet it has 1 more hole that will be left bolt-less if you decide to mate it to the OHV. This hole is used when the HD is mated to the SOHC, meaning the trans is compatible with both motors. I have no immediate intentions of ditching the OHV, but should a great deal on a SOHC motor come up, you have the option.

2) The HD M5OD is said to have stouter syncros between the 1st and 2nd gears. My 1st and 2nd never troubled me, however you cant argue with added reliability. You have to figure, if this trans was meant to deliver the power of a motor pushing around 50 more hp then its predecessor, they must have beefed it up in some aspects.

Now that I have broken down some of the basics, on to the fun stuff. I pulled my first M5OD out of my the 1991 Explorer, this M5OD originally coming from a 1993 Explorer Sport. After that I sat it on the floor next to the new trans to compare differences.

Pictures in a little

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Pics and some info

Here are some Pictures

Pic 1 - Just the two from a from view sitting side by side. The bellhousings are the same overlooking the one extra hole in the HD unit

Pic 2- This pic shows the differences in the 4x4 Extension housings. As BonesDT stated in his thread, these housings have the same bolt patterns but are NOT INTERCHANGEABLE. The 1993 trans has two bolt bosses for manual shift transfer case linkage, while the HD unit has an opening for a OSS sensor and does not have the linkage bosses.

Pic 3- Looking down at the top cover, both trans units have a red 2 prong connector for reverse lights. The older trans oddly enough has one extra connector that runs into the same trans harness on the car, and this is for the NSS (Neutral Safety Switch/Sensor). Its 2 prong as well.




If you do crack the case on the M5OD, I had a similar problem on my 91. Third gear would not shift right, and the trans seemed to be binding. The actual repair was a new 3rd gear and two syncronicers. Third gear had a tiny crack near the inside of the gear. So check gear damage.

$550 is pretty good for a whole new transmission. Especially considering the factory kits for repairing the various syncro issues cost about the same.

i wouldnt mind one of those in my 99 =p i miss manual trans

Ok, bought a few things today.

#1) I tried to buy a freeze out/ core type plug for the OSS sensor. My caliper told me it was about a .865 inch diamter bore, tried a .855 and it was noticably too small. I couldn't get a perfect match at Napa, so I called up the great old Ford parts desk, and priced out the actual OSS sensor. At $31 plus tax, I sprung and ordered it. It is said to work with 2001-2003 SOHC motors, and figuring I might move to the SOHC at some point i bought it.

#2) I bought metal shift rail plugs to replace those cheesy rubber plugs. Total cost was somewhere aroud $1.30 for all 3.

Dana #219-3052 or Doorman #555-108

The only thing left in this swap transwise I still have to determine is what to do about the non-existant NSS wiring on the new trans. I've heard of plugging a resister in its place, to trick the ECU, but in all honesty I don't know what the effect of the absense of this connection will result in. If any of ypou guys know, feel free to help me out, haha.

Ever hear of anybody taking out their 5r55e and putting this manual in? Id love to do it, just not real comfortable with the small things like clutch pedal and cutting a hole under my cupholder. I have a 97 explorer ltd.

Well since you have a 97 LTD you probably have the SOHC and you would need to have the computer reprogrammed for the manual transmission and you don't need to cut a hole since your floor has a removable pan for where the tranny shifter comes through and take your trip computer stuff out and get an XLT cubby hole the cubby hole is removable then you could make your own boot for it or buy one as there is a company that makes a boot for the console.

Oh and Welcome To The Forum!

It's been a while, but...

Hey guys,

I finished this up ages ago but never finished the thread. Found some pictures I managed to take while I was buttoning up the installation, so I figured I'd show you what you are up against if you attempt the swap.

Everything went in pretty smooth. I opted to use my Slave Cyl off of the first M5OD, for several reasons:

1) It only had a few thousand miles on it, no need to discard it
2) Thanks to the Hydro Quick Fitting, it did not require rebleeding
3) The Slave Cyl on the HD trans had a different sized quick fitting, which would have required me to go on a hell of a hunt to track down what year clutch line was compatible with it.

After bolting up the chosen slave, I got the trans mated to the engine block, and tightened up the bellhousing bolts. The only electrical connection I attached was for the reverse lights - I taped over the VSS sensor connector just in case I swapped to a motor in the future that required it. The clutch line went in like butter, no bleeding required. I tucked the wiring out of the way for the NSS sensor, being that there was not one on the new trans.

Everything bolted in smoothly, UNTIL I got to the shift lever. The shifter stump in the old transmission was different than the new one provided with it. The key cut in the shifter stump varied by 90 degrees between each trans (See Pic 1). Attempting to bolt my shifter onto the new stump left my stick shift leaning towards my passenger door, rendering it useless.

My first attempt to remedy this problem led to me taking the old shift stump, and seeing if I could use it in the new trans. This did not work - I had poor movement between each gear, and it did not feel like I was locking into each gear correctly. I believe, besides the key cuts being different, the actual spade end at the bottom was slightly longer/ differently formed in the new trans (See Pic 1, again).

So, not wanting to spend any more money/ spend forever looking for the correct shifter and re-modify it for a B&M Shifter as my current shifter had, I turned to my welding skills to save me. I decided to use the shifter stump that came along with the new trans, and simply cut, turn 90 degrees, and reweld the shifter to face the correct orientation. (See Pics
2-4). This turned out to solve the problem perfectly, at no monetary cost, and maybe 20-30 min minutes of double checking the angle of the shifter before welding it in place.

With everything bolted in, (Driveline, Shifter, Hydro System, and Reverse Lights) I crossed my fingers and turned the key. To my content, it fired up on command, went into reverse smooth, and i backed out of the garage. Driving it around the block, it shifted perfect, and despite not reconnecting the NSS wiring to anything, it did not throw a check engine light.

6 months later, it's still running 100%. Shifts crisp at 4k RPM if I demand so much from it. I HIGHLY recommend this trans upgrade to anyone who is looking to replace the slushbox A4LD or looking for an improved nearly bolt in replacement for their older style M5OD.





Thanks for following up. It's on my list of future mods so this will come in handy.

Pic 2- This pic shows the differences in the 4x4 Extension housings. As BonesDT stated in his thread, these housings have the same bolt patterns but are NOT INTERCHANGEABLE. The 1993 trans has two bolt bosses for manual shift transfer case linkage, while the HD unit has an opening for a ODD sensor and does not have the linkage bosses.

A note on this. The HD was stock in my year Sport, so I didn't have the bosses. When I swapped in a manual t-case, I was able to make a bracket that located the linkage. So it is possible if someone wants to do it.


Awesome followup damarble! I plan on eventually converting over to manual shift, that picture will definitely come in handy.

If I ever kit around to it I'll add a pic of it mounted to show better how it works. It basically spans the area where the bosses should be to make an attachment point.

Did your transfer case bolt right on to the tail shaft with no problems? Did the tranny mount still line up? This is one awesome job you did on this. Very impressive!

Excellent writeup:chug: I made this a sticky thread and extended your Elite status 6 months.

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Just wondering if I replaced my stock manual trans in my 93x with the HD would this mod increase my tow rating? If I've read correct my stock config has a much lower tow rating than if I had an auto trans.