Ok, i am keeping the inline 6. Now my attention is turning to the transmission behind the inline 6. Its a three speed with the shift on the column. The plans are for this vehicle to be driven on the highway, speeds around 70, to 75.

So I have to figure out if this trans will hold up to those speeds all the time.

Is the three speed worth rebuilding?

Do I replace it with a 5 speed trans?

 

After doing some more research, I believe the three speed transmission can handle what I throw at it. So I will just rebuild it and drive on. But still looking for any advice anyone is willing to part with.

 

You didn't mention what power you plan on throwing at it, but regardless, people usually have other reasons for going with a 5-speed with a shifter at the tunnel rather than column.

The easiest route will probably be a M5OD, as used in boatloads of trucks through 1996. Conveniently enough, the V8 and 4.9 share the same bell pattern, so you don't even have to worry about the donor coming from behind a 4.9-powered engine, a 5.0 or 5.8 got the same gearbox.

There was also a ZF 5-speed that was used, but as I understand it, that was typically found in 4WD configurations while most of the 2WD got the M5.

 

Well at first I was thinking the three speed couldn't handle todays highway speeds. So i was thinking about replacing it with a 5 speed for driveabllity. But if the three speed can handle it than thats the way I will go. Plus it would be nice to keep the shifter on the column and not cut a hole in the floor.

 

Close. F-150 = M5OD. F-250/350 = ZF5.

Both came in 2WD and 4WD, the ZFs are just a heavier duty transmission.



I can't remember, do you currently have a 300 in the vehicle? Or planning on putting one in?
Depending on what engine you currently have in it, your current transmission may not even bolt to the 300.

 

The engine is a 240 cid

 

I prefer the grany low 4spd ( NP435 ) , but I'm just weird!

If you are just using your truck as a driver the 3.03 3spd will be fine.

 

LD F-250 = M5OD. HD F-250 = ZF5. 2WD anyway 'cause that's what I have in my LD. IDK about 4WD.

 

Thanks brother, that is what I was needing to hear.

 

if you go with a 5 speed, you can get overdrive which will drop your cruise RPM at freeway speeds. Plus with the lower first gear on the M5R2 you can probably go with even higher rear end gears to effectively get a "double OD". At least that's my plan. The OD will either help with gas mileage or allow me to drive faster. Hmmm... wonder which one I will pick?

TR

 

Good and well until you try to back up an incline and find out the Madza tranny has a reverse ratio that's way too high. Unless you have 4wd and low range, forget ever backing a trailer up a grade without smoking the clutch. The M5R2 might be easier to find but I'd hold out for a ZF if I was going to the effort of switching over to juice clutch.
Don't forget there were at least 3 different 4 speeds with 4th overdrive and they will bolt up to your existing bellhousing so the clutch linkage you have will stay the same.

 

My '86 already has a hydraulic clutch.

Don't plan on using my truck to tow massively heavy loads.

For me the grannie first gear is worthless.

TR

 

will the 3-speed hold up? absolutely.

would i want to run 70-75 without overdrive? no.

 

I didn't know there was a light duty of the F-250. Good to know.
I guess it's better to say that light duty = M5OD, heavy duty = ZF5.
Not going to find a heavy duty F-150, and you're not going to find a light duty F-350.

I think that depends on the differential ratio. If you have a 2.73 or a 3.00, 70 - 75 without overdrive isn't an issue since the RPMs will be lower. I'm at 2500 RPMs at 75 with 31" tires an a 3.00. My wife's Bronco with 3.55s and no overdrive is a different story... and we're looking for a 5 speed for her.

 

Three on a tree? Keep it. With just a little work that 240 will be right in the sweet spot at highway speed.