3rd Member Compatibility (1 Viewer)

O-k,

I am looking for a third member to swap into my 1978 FJ-40. It was built in 09/77 - important because I have a coarse spline pinion.

I have the chance to get a third from the front of a 1969 FJ-40

A few questions for my MUD brothers and sisters though...

I think the axle spline count is the same from 1969 to 1988 - correct?

SOR distinguishes third members from 1969 -1/74 as different from thirds from
1/74 - 12/78...

Why?

I thought it must be flange differences, but wouldn't a 1/78 flange be
different than a 12/77 flange? (fine/coarse pinion)

But when I look at R&P sets, SOR breaks them at the 1/74 date as well...
What is going on here? What changed btwn 12/73 and 1/74?

Will a front third from 1969 fit the rear diff housing of my 1978 (09/77
production date) 40?

I will use my flange, change pinion seal, etc, but will everything fit right up?

TIA,

one thing about the 69

the ring is mounted by bolts going thru the carrier into the ring.
some others like my 84/60 has a nut and bolt combo to mount the ring.
thats one difference that i can see....

carry on

woah....

diffs are identical, you'd need to swap the center block from the rear 77 to the front 69 to keep your c-clips in place...and you'd need to switch d-shaft flanges since the 74-older 3-speed pattern is not the same as the 74+ 4-speed pattern, even tho both may be coarse spline pinions.

ring gears changed from a threaded ring with bolts to bolted/nutted ring gear....carrier is identical.

Sweet!

Thanks Jim! Thanks Woody!

wish i knew that much..

woody, you are the man

Are the companion flanges compatible?

Can I mix and match all coarse spline companion flanges?

Or, to put the question another way, can I put my flange from my coarse '78 third onto the '69 third?

W/o fawking up this '69 third? Are the depths of the flanges all the same?

The '69 pinion uses a cotter pin to secure the flange nut, while the '78 pinion uses a stake nut...

Thanks,

flanges, within spline groups, are completely interchangable...depths are all the same.

Really, depth is irrevelant, it's the torque that's critical.

Running the 78 coarse flange with a 69 pinion and using the castle/cotter is no problem