1985 F250 Manual Transmission

According to the door tag it’s a code K, but when I look at the certification label table on this site it’s says its a C6. The main question is can I put this transmission on my 81 f100? Thanks in Advance.

So you currently have a manual in your 81 F100 and you want to swap it for a C6?

What size motors on both trucks.
They 4x2 or 4x4?
Long beds or short bed?
250 would be long bed

Dave. ----

My 81 has a 300 inline 6 three on the tree (guessing is a C6?)

Both 4x2.  The 81 has a 300 inline 6 and the 85 250 has a 302 according to the VIN.

Three on the tree I’m guessing a C6

I think the F250 has a T-19 Borg Warner.

Ok a 3 on the tree is not known as a auto transmission.
3 on the tree is a 3 speed manual, 3 pedals at the floor, gas / brake / clutch.
A auto transmission can be a 3 speed but only has 2 pedals on the floor, gas / brake.

If the motors are a 300 six & a 302 the bell housing from the manual will swap with the auto motor.
Now the flywheel & flex plate WILL NOT SWAP as the weights are different between the motors.

You did not say if long or short beds so cant say on drive shafts.
You will also need to deal with the steering columns as 1 has a shift lever and the other dose not.
Dave ----

Thank you. Yes, after further research the 81 F100 with a inline 6 300 has a 303 standard transmission and it’s a short bed. The 85 F250 has a 302 with a T-19 Borg Warner transmission and it’s a long bed. I have procured the required  column already.

Yes, I have found the hard way (previous project)the difference on weighted flywheel/flex plate issue.

If the F250 bell housing fits the 300 motor, the T19 transmission ratios are insane!.  Should I get another shaft or can I use the shirt bed one? What about the rear axle? It currently has a 2.47.

The 250 would have a T-18 transmission. (no PTO on the driver's side)
T-19's came behind 460's and IDI's only.

The T-18 has a very deep 1st gear that would probably be well suited to your tall 2.47 rear end.
But 1st is not synchronized, so you will have to get good at double clutching and rev matching.

Socnarftrucks wrote

Thank you. Yes, after further research the 81 F100 with a inline 6 300 has a 303 standard transmission and it’s a short bed. The 85 F250 has a 302 with a T-19 Borg Warner transmission and it’s a long bed. I have procured the required  column already.

Yes, I have found the hard way (previous project)the difference on weighted flywheel/flex plate issue.

If the F250 bell housing fits the 300 motor, the T19 transmission ratios are insane!.  Should I get another shaft or can I use the shirt bed one? What about the rear axle? It currently has a 2.47.

BTW that 250 trans might be a T18 unless some one swapped it in as the T19 came with 460 & diesel motors but  not a big deal if it is a T19 or even a NP435 as they all swap between them.
The T19 has a syncro granny 1st gear where the T18 & NP435 do not.

The T19 bell housing & trans should bolt to the 300 motor.
You will need to cut the floor for the shifter pan from the 250 and bolt it in.

You know about the flywheel balance but if the 300 has a flywheel you should be able to use it.
Thing is if the 303 clutch will fit the T19 input shaft? I know the 300 came with a T18 so that clutch kit should fit the T19.
The only other thing on the clutch is they say some flywheels are drilled for both the 10" & 11" clutches.
I dont know if the 303 flywheels are drilled that way and I did not know this when I did the clutch on my truck to look. Think mine is a 10"

On the drive shaft you would need to check that as I dont know the answer.
Do both transmissions have slip yokes or is the T19 a bolt on drive shaft?
If slip you would then need to test fit the 303 to the T19 if it will fit.
If not you could swap the 2 slip yokes even if the Ujoints are different sizes as they make ujoints in different sizes just for this.

Now that brings us to the next part, transmission sizes.
Measure from the face that bolts to the bell housing to the end of the tail housing and if the same then you might be able to use the short drive shaft with the above yoke swap.
Other wise you will need to get a new drive shaft made.

As for the T19 ratios I dont see that as an issue.
My 81 F100 with 300 six came with a T18 (granny first gear) and 2.75 rear gear from the factory.
I swapped in a NP435 (granny first gear) and a advance adapter over drive keeping the rear gear.
The 2nd gear ratio (that you startin 99% of the time) between the T18 & NP43 the 435 is a little higher (more clutch slip but not bad) but other than that is not any different.
If I need to pull a heavy load, car trailer, I have the granny gear to get the load moving and then can shift to 2nd gear or with the over drive I can split all the gears as needed.
So could start in granny over drive and shift to 2nd direct> 2nd OD> 3rd> 3rd OD> etc.

Hope that helps a little
Dave ----

Just a thought that 85 250 what type of clutch dose it have? if hydrolic then the linkage from the 303 trans may not work?
You would need to look deeper into that.

Thank you all for sharing your wealth of knowledge. It’s truly appreciated and motivates me to keep going with this project knowing I not in this all
Alone!!!

We are here to help as much as we can.

I know when I swapped out the T18 for the NP435 with help with measurements I was able to tell it was a bolt in if the drive shaft yokes were the same as what my truck had, slip yoke.
Because I added the over drive unit is the only reason I had to have a new drive shaft made.
Wanted to keep the old shaft so if I wanted to remove the OD and run just the trans I could.

The only reason why I say  to use the 250 bell is I think the 303 bell  is not drilled for the T19 trans and may not be deep enough.
Just dont know how the clutch works on the 250 if that bell could be used on the 150 truck with linkage.

BTW make sure the linkage is in good shape on that 300 motor truck.
The Z bar pivot on the motor side you can no longer get but can get the bushing for it.
So if it should break off the motor you will need to fix it, like I did 2 times, or swap to a juice clutch, maybe from the 250?
Dave ----

Dave, the T-18/19 both use the common Ford 'butterfly' transmission bolt pattern.
I know nothing about a 303 gearbox input shaft, but the bellhousing itself should fit.

That would be great news because there wouldn't be a need to adapt an '84 & up hydraulic pedal assembly and master cylinder to an early truck.

ArdWrknTrk wrote

Dave, the T-18/19 both use the common Ford 'butterfly' transmission bolt pattern.
I know nothing about a 303 gearbox input shaft, but the bellhousing itself should fit.

That would be great news because there wouldn't be a need to adapt an '84 & up hydraulic pedal assembly and master cylinder to an early truck.

That was my thing not knowing the 303 bolt pattern to the bell, but my thinking it would be more like a car  4sp top loader. If the 303 bell is drilled for the granny 4sp. and is deep enough then he would not need to swap bell housings.

Now if he dose need to swap if it uses the slave on the outside he might be able to not use it and keep the manual linkage and make the adjustment between the Z bar & fork.
IIRC he has a 300 six so the motor side pivot is on the motor and he needs to take care of it as you cant get it.
Dave ----