rearend size

does anyone know what size ring gear is in a 1978 impala wagon

8.5" 28 spline center section.

Rear end size?

"I like 'em round, and BIG!"

Sir Mix-a-Lot

jayoldschool wrote:

8.5" 28 spline center section.

I do not think the 8.5" axle was used in the wagons. If I remember correctly the wagons used the 8.75 BOP axle. I know that was what was in my 78 Impala, and that is what is in my 78 Catalina Safari.

They have a 12 bolt ring gear (number of retaining bolts) and a 10 bolt cover. Most of the ones I have seen have the fill plug on the back of the rear cover, not cast into the center section where most GM axles have it. Not a 100% ID as the earlier 8.875 version of the same axle. (not to be confused with a true Chevy 12 Bolt axle that uses the same size but not interchangeable ring gear)

A strong possibility, that's what's in my 81 Fleetwood, too!

cammerjeff wrote:

jayoldschool wrote:

8.5" 28 spline center section.

I do not think the 8.5" axle was used in the wagons. If I remember correctly the wagons used the 8.75 BOP axle. I know that was what was in my 78 Impala, and that is what is in my 78 Catalina Safari.

They have a 12 bolt ring gear (number of retaining bolts) and a 10 bolt cover. Most of the ones I have seen have the fill plug on the back of the rear cover, not cast into the center section where most GM axles have it. Not a 100% ID as the earlier 8.875 version of the same axle. (not to be confused with a true Chevy 12 Bolt axle that uses the same size but not interchangeable ring gear)

as was mentioned its a 10 bolt 8.5" with 28 spline axles,same as 1/2 ton truck basically.

My point was it is not a 8.5 axle but a 8.75 axle. Completely Different Axles.

I agree they were also used in light duty Trucks and B-Body Wagons and some Caddies of the same era. I have heard that they may also have been used in B-Body Buicks Sedans and 2-doors when the Towing package was installed. But I have not seen a Buick non wagon with one.