I have a 6.9 Diesel Engine (that used to be attached to a T-19 tranny) on the hoist right now. Its going in my 1981 F-350. I pulled the 351m out of the F-350 and want to now put the 6.9 Diesel in. Will the 6.9 Diesel bolt on to the T-18 4spd that is currently in the F-350?

Reason why I want to use the T-18 instead of the T-19 is:
The T-18 is a mechanical clutch and the T-19 is hydraulic. If I put the T-19 in with the diesel, ill have a bunch more work to do, and i'm okay with the T-18 being behind it.

Question is, are the two transmissions completely interchangeable? Can i just drop the 6.9 in and bolt it to my old T-18 that used to be on the gasser? I ask because i know some transmissions are gasser/diesel specific.
Thanks,
Billy

 

Yup!
Plug and Play!

-Enjoy
fh : )_~

 

The only difference I think between the t18 and t19 is t hat some of the T19s had a syncronized first gear, whereas the t18, like the NP435, have non- sync first.

 

I could have been a lot more clear... The transmissions are an exact change.

The bell housings are not, the Gasser bell housing will not fit the Diesel.

-Enjoy
fh : )_~

 

Personally, I like the T19 better. I prefer the synchronized 1st gear and the fact that the version most often used behind the 6.9 was a true four-speed and didn't have granny low. I put one in my '68 F250 and am very happy with it.

The clutch actuation really has noting to do with the tranny, it's dependent on the bellhousing and of course the system that's used in the truck. I bolted the T19 which came out of an '86 truck with a 6.9 and hydraulic clutch into my '68, bolting it to the stock bellhousing with mechanical clutch in place of the NP435 that was in there originally.

For what you're planning to do, you'll have to use the 6.9 bellhousing which is built for the hydraulic clutch. You may be thinking that the 6.9 will bolt to the 351M bell as it looks the same, but it's not. It's very close, close enough that it looks doable but it's different, trust me, I know...been there, done that! So you're going to be fabricating something to either adapt the truck's mechanical linkage to the 6.9 bellhousing, or getting the entire clutch hydraulic system from a later truck and swapping into the '81.

EDIT: I started typing the above after the second post and got distracted, just got back to it and finished up only to find the two new posts above so, yeah, what they^^ said...

 

I anticipated issues with the bell housings. Would it be easier to just put the 6.9l, attached to the t19 into the 81' and swap all the hydraulic components into the 81'
or
fabricating the current mechanical linkage to the 6.9 bellhousing.

 

I think it would be easier to swap the 6.9/T19 assembly as a unit. I'm not sure about the hydraulic clutch, if that would be the easiest way to go but I'd suspect so. Since the later trucks of this bodystyle came with hydraulic clutch anyway, I suspect it would be a bolt-in or very close to it.

Benn a while since I messed with one so I don't remember...does the slave cylinder push forward on the linkage, or backward? If it pushes forward, then it would be much more complicated to convert it to a mechanical linkage.

 

Swap it all... Is what I would do, Unless the T19 is in worse shape than the T18. Then I would still swap it all except for the transmission itself.

-Enjoy
fh : )_~