i have a 87 formula that came with a 5.0 and 4 speed auto with posi rear.i have swapped in a old style 350 chevy and a old 4 speed manual trans.i have been searching your forums and have not seen anyone else using this set-up.is there a reason for this?also it has the manual clutch linkage and i installed the jegs torque arm kit that bolts a new shorter tubular torque arm to the body not the trans, so you can run any trans you wish.everything went in fine and easy.i now need a driveshaft.i know that 82 came with a four speed, is this the only car that came with the driveshaft size i need?anyone know of any others?also anyone know what kinda gears came stock in these rears.it is posi and they feel very low..(drove car once with new motor and trans and couldnt get outta first):lala: im really just wondering if i shoulda went a different route but i want a fun car more than a insane bracket racer.

 

Plenty of people run a combo like this. There's nothing inherently wrong with it.

I think the 4-speed was an '82 and '83 only option, but I won't swear to that.

You can look up the rear gear ratio the car had stock by using the RPO codes inside the console compartment. This site has a decoder. If it was a V8 car I don't think it could have come factory with anything over 3.42s. I know some cars got factory 3.73s, but I think they were V6s. Again, I'm not 100% sure of this. The best bet is still to pop the cover and count up the teeth or rear the markings stamped on the pinion head.

 

HO equipped cars got 3.73 gears with the 5 speed.

I've been wanting to do a 4 speed swap for quite a while, but I can't find any good trannys to use for it.

What type of four speed are you using? T10?

 

i really dont know.i went through plenty of saganaw sticks in my old car.i would dump it and make mince meat out of first gear.but i got this one used at a speed shop.it is very tight, no torque arm bolt holes, and i put it through its paces and haven't hurt here yet. the swap was very easy.just gotta find 82-83 clutch brake pedals with the z-bar and bell housing.i got mine on ebay.clutch works great.....i need a driveshaft.any tell tale signs on what trans im using?any way to distinguish?i heard this trans was outta an el camino?i dont know how much truth is in that tho.

 

As far as identifying it, hopefully it's an aluminum case as those are the only four speeds really worth messing with. If it is aluminum, a muncie four speed has 7 bolts on the side cover and the borg-warner super T10 has a 9 bolt side cover. You should already know how to identify a saginaw. Saginaws are cast iron, and reverse gear is in the side cover instead of the tailshaft housing, Muncies and T10's both have reverse gear on the tailshaft housing. Unless you want to have another driveline modified to the correct length, the only ones that are the correct length are the 82-83 four speed ones and the 82-83 three speed automatics(TH200 if I remember correctly).

 

great info...it is cast aluminum as far as the others, im gonna have to look.thanks for the auto 82-83 shafts.i didnt think of those.im trying to find a needle in a haystack.
Also another question??
the 3rd gens. with the v-6 and manual ,are those 3.73 rears in them worth looking for?are they beefy for a 350ci.?
also did they make those rears with disc brakes?:hail:

 

Ford Toploader 4-speeds and Mopar 883s both use and iron case, as do some early T-10s. Heavy, but plenty strong.

 

3.73 gears are worth getting, but they never came behind a 350 car (not in 3rdgen for anyway). Only the HO 305s got them.

 

the 3rd gens. with the v-6 and manual ,are those 3.73 rears in them worth looking for?are they beefy for a 350ci.?
also did they make those rears with disc brakes?