1978 L80 WS6 rear end

[Maxthe222]

Hey gang,

What was the factory ratio for a 1978 WS6 L80? In 1979 you got the series III with a 2.73, is that the same for 1978?

[firebirdparts]

Most of them are 2.41.  In 79, a WS6 with no air conditioning is 3.23

[edit] In 79, WS6 with air conditioning is in between at 2.73.  But 1978 WS6 L80's are so rare, I don't know for sure what they are.  I went through my build sheets and didn't find any 78 403's at all.

2.73 to 4.56 and/or infinity is same carrier on that car, yes.

[ryeguy2006a]

I thought that a series 3 carrier was for 3.08 - 3.73?

[Wallington]

On an 8.2 centre perhaps, on the 8.5 it was 2.73 and up were 3-series. Only 2.41 - 2.56 were 2-series. There was only the 2 versions for the 8.5 centre and even the terms 2 and 3 series have stuck from other diffs and don't accurately apply, referred to as high or low series in some literature.

[firebirdparts]

I thought that a series 3 carrier was for 3.08 - 3.73?

Nope.  2.73 to infinity.

Pre-1970, all bets are off unless somebody tells you (without being wrong) what axle he's really talking about.  Each division had their own axles, none of which was the axle used in a 1978 firebird.

[Maxthe222]

Hmm, i'm changing the diff oil so i'll check the gears when I do, but there's nothing to say it wasn't swapped (which isn't likely but still). Previous owner threw away buildsheet that was under the seats, only found bits of it. Car is completely torn up in some ways but untouched in others, i'm hoping buildsheet is on petrol tank still since it's a Van Nuys car.

[langss]

Hmm, i'm changing the diff oil so i'll check the gears when I do, but there's nothing to say it wasn't swapped (which isn't likely but still). Previous owner threw away buildsheet that was under the seats, only found bits of it. Car is completely torn up in some ways but untouched in others, i'm hoping buildsheet is on petrol tank still since it's a Van Nuys car.

Not trying to burst your bubble or rain on your parade, but I had the tank down and the back seat out of my 78 and there was nothing there in either location. Now on the beater 78 Z car, I found one just laying on the carpet under the drivers seat, one stuffed up under the dash, and one under the spare tire. Sad thing was that poor car had been so abused it would have cost a "Kings Ransom" just to make it a decent driver.... Both were April-May Van Nuys builds.

[sparky]

I have a 78 TA I bought new out of the show room in December of 77. I recently lifted the rear seat out and there was the build sheet on the passenger side.
My automatic came with the 2.56 rear end ratio.

[Maxthe222]

I have a 78 TA I bought new out of the show room in December of 77. I recently lifted the rear seat out and there was the build sheet on the passenger side.
My automatic came with the 2.56 rear end ratio.

Was that a 403 Oldsmobile carrier? 2.56 would be better than 2.41 but it just misses out on a series III