Bob Kelso

I have a 28 spline o-axle 3:08 open rear end with the casting numbers 393820 and the code on the tube is SC . The question i have is it has a big M on the cast iron center section between the yoke and the top where the rear cover bolts . I have not seen this before and would like to know what the M means . I have seen the big N on the Pontiac rear ends for Nodular but never the big M on any of these rear ends . Thanks BOB

monzaz

Bob, Please provide pictures of the rear Thanks, Jim

What year olds does this fit?

Bob Kelso

I don"t know what specific car it came out of , i acquired it in a trade . It is a 28 spline axle with the early sealed bearing with the seal in the housing . It has the std measurements for the mounting locations and is an Olds o-axle A body housing . . BOB

monzaz

Really have not seen one yet. Pretty neat. Maybe it si a VERY early casting and the ones after it do not have the M

It has to be 67 or 68 since it is a sealed bearing. What is the flange to flange width? jIM

CAN I ASK A QUESTION... WHERE THE H-LL ARE ALL THOSE REARS AT??? I WANT THEM!!! REALLY. JIM

507OLDS

What is the casting number underneath?Does it look like it was modified at all,like the control arm perches rewelded?I am trying to figure out what I see in the last picture.It could possibly be a 350 Delta O-axle,that someone modified & welded the A-body perches on,but it would still be wider,unless they cut it down too.

Bob Kelso

It has not been welded or modified , it measures out for the std width A body rear axle . As stated in the first post the casting numbers in the rib was 393820 , date code of 323 . I have had a lot of the o-axle rears and this is the only one i have seen with the M on it . The code of SC on the tube matches the 3:08 open inside . Yes it is not the 70 style axle bearing , it is the 67-68-69 style axle bearing - seal set up . It is the 28 spline axle . BOB .

Bob Kelso

I measured the distance from the outside of the axle flange to the outside of the axle flange and it is 61 inches . On the back side of the axle is the number 907 cast into the flange . BOB

monzaz

So bob are you measuring the total width or the housing tube width?

How long is a axle shaft ? FULL LENGTH?
The rear under the 12 bolt olds rear seems to be a Nova rear which is 54 1/4 flange to flange or 60" over all drum to drum and your rear above it is WAY wider so this would be a FULL size rear...??? Sure no one has messed with this rear? close up shots of the welds what is the axle wheel bolt pattern 5 on 5 or 5 on 4 3/4?

What does the yoke look like? Thanks for humoring us with this rear. I am really trying to figure this one out. NOT usually stumped but this is a little weird...Jim

Bob Kelso

Bolt pattern is the 4 3/4 std one for the A bodys . It is 55 1/2 inches out to out of the axles tubes , measured at the mounting flange for the axle , . The measurement for the out to out of the axle flange , where the brake drum sits , is as i stated , 61 inches . Center to center of the spring perches is 35 1/2 inches , inside of the yoke measures 2 1/2 inches . This is where the internal flat area of the yoke where the snap ring will sit . This uses the u-bolt with nuts and washers for the u-joint retention . It is the short yoke that is used on the o-axle . I measured a 1970 o-axle housing and the same measurements came up . BOB

1970cs

See if this helps!http://wildaboutcarsonline.com/membe...2_-_Sec_5_.pdf
see page 13 it has the right code and ratio! Source 1970 Olds CSM

Regards, Pat

monzaz

Well ALL that points to A-body 12 bolt Olds...??? Just never saw the M before. NEAT. Very neat find. Now we just have to build it. lol. Jim

11971four4two

One of these showed up here today. It was removed from a 1967 cutlass. I had not seen the large M housing before. interesting

monzaz

1ST YEAR THING? Even the castings on the cast support webs resemble the early 8.2 olds/ ontiac housing in 1965. Might be a certain plant - or some factory special one off run housings... ???