So I'm in the process of swapping my transmission out on my 1980 f100. Truck was originally a 3 sp on column and I am changing over to the M5OD to give it some extras gears, truck is just a cruiser nothing fancy. I know all about what I need to do as far as the new hydraulics for the clutch goes but I'm not sure about the clutch itself. Do I get the new clutch pressure plate assembly for the 80' or get one to match the new tranny which is out of a 90'? transmission is being bolted to the current 300/4.9 that came in the truck. Just wasn't sure if there would be any differences in the clutches between year models and different transmissions. TIA

 

Do you know what motor the M5OD was from?
So here is what I would do be it right or wrong.
I would look up clutch kits for both years with the 300 motor and see if the part numbers are the same.
Now be careful as the throw out bearing maybe different and kit numbers change.
So maybe look up just the disc for both.

The other thing to look up for when looking up just the disc is size. yours maybe a 10" disc and the 90 a 11" disc and number be different.

Now on the disc if you have your truck apart and can check the flywheel it maybe drilled for both a 10" & 11" disc so I would go for the larger one.
Also if you have your truck apart and the M5OD trans try your disc on the M5OD and see if it fits the input shaft, that is the best way.
I think after all that I would go for the 90? clutch parts as the disc should fit the input shaft and the throw out bearing work with the clutch fork.

Center Force had a break down of disc & parts you could look up by year and match up parts numbers. I had to do this when I went from a 4sp to a 5sp od in a older car using a mix match of parts from 2 different cars, not the one I was working on, and Jeep clutch parts.
Dave ----

 

I would make sure to get a clutch for a 90 so it fits the trans. The transmission dimensions can be different, but the back of the engine was the same. I would do what the other Dave said and check the flywheel numbers, you may need a 90 flywheel also.

 

Assuming when you say 3 spd on the column you mean a three-on-the-tree manual? If yes, I have done this exact same swap, and it's easier than most. The M5OD is only about 3/8" longer than the 3spd manual, so you can re-use your existing driveshaft and slip-yoke and all, it literally swaps right over to the 5spd without modification. You can also plug your original speedo cable right into the 1990 M5OD. I was lucky when I did mine as my truck and the one the 5spd came out of both had 3.08 rear diffs, so my speedometer even stayed correct without having to change the speedo gears.

The 3spd came with a 10" clutch in the F100, and the M5OD came with an 11" clutch. I had my existing flywheel cleaned up and surfaced and installed a new 11" clutch to match up with the M5OD. My truck was an '84 and the original flywheel was drilled for the larger 11" clutch already.

Other good news, and not that it matters much, but you can use a Bullnose clutch master cylinder with a hydraulic line and slave cylinder from 1988-1991. They work together just fine.

I've done two M5OD swaps in Bullnose trucks and I really like this transmission. (one an '84 with 302 and 3spd, and the other an '80 with 300).

 

Dave, I forget how many splines are on the trans input shaft (10?) but I do know they're the same on the 80's transmissons and the M5OD. Pilot bearings are the same also. Flywheels were all the same, and they should all be drilled for both 10" and 11" clutches, but I'm not 100% sure on the very early 80's ones. By 1984 they were all drilled for both. The M5OD has the internal concentric slave cylinder that is integrated with the throwout bearing...they are one in the same part.