1979 Spider Gears Differential

[Schanen C.]

Hi All,

What for Spider Gears are the correct ones for my 3.55 Original Diff.

I have found 2 Numbers 9778343 and 3958108.

I have found No Numbers in my AIM.

Thanks

Rgds.

Carlo

[Joe L.]

Re: 1979 Spider Gears Differential

Hi All,

What for Spider Gears are the correct ones for my 3.55 Original Diff.

I have found 2 Numbers 9778343 and 3958108.

I have found No Numbers in my AIM.

Thanks

Rgds.

Carlo

Carlo-----

The "spider gears" consist of 2 side gears and 2 pinion gears. The side gears were GM #3869317, 2 required. The pinion gears were GM #9778343, 2 required.

The GM #3869317 was discontinued in October, 1976 and and replaced by GM #6260528 which is also discontinued as of February, 1999. I believe the 6260528 was a set of both the pinion gears and the side gears. I'm not sure, though, as it could have been just a set of side gears (I should know the answer to this as I have a GM #6260528 [not for sale] but I just don't feel like going out to find it).

The GM #9778343 was discontinued without supercession in March, 1994.

You may be able to get these parts through aftermarket sources. Gary Ramadei should know.

By the way, you won't find these parts in the AIM because the differential was delivered to St. Louis as an assembly, not the individual pieces thereof.

[Gary R.]

Re: 1979 Spider Gears Differential

Hi Guys, as Joe stated the Gm spiders are long gone. The aftermarket spiders are still available and are a quality part. I have been using them for years. One word of caution the spiders and clutches sold in the assembled posi's are not the same as originals or what I use. Rarely spiders are bad unless the diff is blown up. 76-77 diffs have some areas to check if you have yours apart. Side yokes are soft, RG Bolts are flange heads and not loctited in place, the clutches are the much weaker snow flakes.