yellow-fever

I am ordering a rebuilt differential from Eckler's. You have to specify front yoke size, either 3.75" or 4.25". I was surprised my 74 big block had the smaller 3.75" yoke. Then Ecklers called me to ask me whether it was an auto. or manual (mine is a TH-400). So did big blocks come with the larger yoke or did manual trans. cars? What's the deal?

1Fordman

If I may venture a guess, the manual transmission cars can be subject to much more stress loading than an automatic. that would be one reason for a larger yoke on a stick shift car.

yellow-fever

That's what I was thinking too.

hogwash

Interesting,I have factory 74 l-82, muncie 4-speed,3.56gear car.how do you measure that,is the u-joint different.I could check mine.I thought they changed the half-shaft& or side yoke size at some point.I'm planning to do some work back there,to fix a side yoke leak.I'd like to beef mine up some with new parts

knkayotte

For reference, my 72 auto has 4.25 yoke.

Sergio305

Hey Yellowfever, I'm about to do the same exact thing you did a few years back with regard to the new rear end differential. Couple of questions: were you ever able to confirm if the front yoke diameter of 4.25 was a BB/SB difference or if it simply was a size based on whether you had a A/T or manual?

I have a 327 with A TH400 and needed to confirm the front yoke diameter before ordering from Ecklers also...
Btw, how are the 3.73 gears treating ya?

redvetracr

take a look at the trans yoke, u-bolts w/nuts or straps & bolts. maybe someone used an earlier diff with the smaller pinion yoke and used a combination u-joint to make it work.