I'm looking to build an early 80's F150 2wd short bed with a mildly built 351W. I want a manual transmission in it. Does anyone have a recommendation for one? I know those years had straight 6's with 4spd or 3sp w/OD but I heard they are weak.

 

The Mazda built 5 speed was not the strongest but it was a good tranny...as long as you don't abuse it, it should hold up fine...I have a 1990 F150 XLT SWB 4x2 with the 300 & 5 speed...had it for 17 years, towed my classic mustang with it and with the trailer...that was about 5,000 lbs......

the only thing these tranny's were prone to was the seal/gasket at the top of the tranny (at the shifter) would dry/rot out and leak.

1st gear is pretty low which IMHO I had 3:55 gear in the diff and you could easily go with 3.25 or even 300........2-5 was real nice as far as spacing/power range, etc.

 

Stangfan, A lot has to do with how you are going to use the truck.
The 4sp (T18) has a granny low 1st gear and was used with 300/six up to bigger v8's it will stand up to a lot as it is a "truck trany". The sister T19 is also a good "truck trany" with a syncro first gear.


The 3sp OD (SROD) I hear does not have a good gear spread. Large RPM drop between 3-4 along with a "high way" rear gear to meet gov. MPG was not a great combo and even less with a load in the truck.


Above you hear of the Mazda built 5sp.Weak if you start pounding the gears.


Others will most likely post about the ZF 5sp OD found in newer truck that they swapped into our older trucks. Do a search for ZF trany swap. I have seen posted it is the hot setup as it has good gear spacing and shifts nicely and is all syncro.
I hear it is a bolt in but will take a hunt to find one to fit your motor as the bell housing is part of the trany. Also I seen posted used ones are pretty used up and needing a rebuild. So might be best to buy are built and maybe eat the core $$.


Now you say mildly built 351 so I am thinking "hot rod" and not a working type truck? If it will be used as both the ZF I think it the way to go.
If hot rod then maybe look into a car 4sp or see what 5sp OD you can find that will stand up to the 351 power. I would not go with a Stang T5 as I think it would be too weak if you start pounding gears. I do know of a member on here that is running a T5 behind a AMC 390 in a heavy car but I am sure he is not pounding gears with it.
I also have a built up T5 behind an AMC 360, not on the road yet and don't plan to pound gears with it.


Just my .02
Dave ----

 

RUG SR-OD Single Rail 4 Speed Overdrive: 1978/83 F100 2WD & F150 2WD/4WD 300/302

This trans was originally designed for mid sized Passenger Cars, but...

Ford began planning to install it in F100/150's during the first Arab Oil Embargo, when a gallon of regular jumped from 25 cents to a buck a gallon, sales of gas guzzling pickups sank like a stone.

 

Thanks everyone. I looking to build this truck for fun not work.

 

Well I don't think any of the tranys that came in our pickup's would be ones to use as they are weak or truck tranys so don't shift well.


You want something like the WC T5 for shifting and OD but a little stronger.
Maybe Google T5 tranys to see who sells them and talk to them to see what they have to say.


T56 trany would hold up but it is tall so would need to cut into the tunnel to make it fit.
Cross member & driveshaft you would have to make.
Shifter as with any trany not made for our trucks you would have to make also.
Also sit down when looking at T56 trany prices but they will hold up to any thing you can put in front of it.


Just my .02
Dave ----

 

ZF-5 is the way to go, But Most of the ZF's were made for the "big block" configuration, 460 and diesel.
You must hunt for the "less popular" small block ZF. this will bolt onto the 351, 302 and 300 six.
I "ran" into a small block ZF from a guy that bought it for his 460, tried to install it and found it was too small at the bell housing.
His loss was my $400 gain!

 

And how is that ZF at speed / power shifting?
Again it is a truck trany all be it a much better shifting one but far from a fun shifting car trany.


Just my thinking but the poster may like the ZF shifting?
Dave ----

 

HI Dave, It's not installed yet, Still have my NP435 "granny gear" in it.
I have been doing an "all year" gas mileage recording/testing, to get some real good mileage numbers since the 435 has no OD.
maybe this winter swap in the ZF.
Yes, it a truck based tranny, "Speed or Slap" shifting, this is not the one for you, Go find a car for that, But my intentions is to do this swap once, and have durability, and the truck is not going to visit the drag strip.
Hauling and cruising for me!

 

I agree - the ZF is a very good tranny but it is a truck tranny and shifts slowly. I had a guy try to speed shift mine and the synchros were never the same afterward.

 

That was the point I was trying to point out on the shifting of the ZF trany.


It sounds like a good shifting modern day truck trany and for hauling and light cruising with OD is the way to go.


Being he is building a hot rod I don't think it is what he is looking for but for what is out there for us is a good choice.
I would still look into a WC T5 with hop up parts if it may hold up to what he is looking to do with the truck, Other wise T56.
Dave ----

 

Maybe I miss spoke on the T5?
https://www.ford-trucks.com/forums/1...-bullnose.html
I did not read thru all of it but maybe reach to the person to see how it is still doing?
Dave ----