jensenracing77

i took this O type posi apart to rebuild it. i marked everything left and right that came out of it. i think i know the answer to my questions but i will let you guys tell me for sure. it is an SH code 3:42 with 28 spline axle and i have an axle that has a little twist to it. i figure it is junk but what do you think? also will the axle from a 70 Vista open rear fit? what about the backing plates? my backing plates are very pitted. i plan to clean everything up good and have a local shop put it together with new bearings and seals.

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2blu442

I don't know about the axle interchange but the Vista Cruiser backing plates will interchange and give you the 2 1/2" wide pads rather than the 2". If you have good Vista drums that would be a nice upgrade. The other possibility would be to get the backing plates/drums from a 1976-77 Cutlass. That would provide the same 2" shoe width but 11" diameter instead of the 9 1/2". I believe these are both bolt on swaps and that there are some old threads that discuss these upgrades. If your swapping out the backing plates "might as well..." John

jensenracing77

is there a date code on these rear ends? i want to keep the original size brakes because it is going in my Rallye 350. eventually i will rebuild the rear end that is in the Rallye 350 also. they are both the same rear end. if there is a date code or something i may have to use the rear that is in the car now.

svnt442

That axle is junk. Once the splines start doing that they are fatigued and it needs replacing.
I think there is a date code on the housing somewhere, but I don't know the ins and outs of decoding it.

2blu442

I know there's a casting number that shows its a 1970 as one of the other guys was looking for one last year and he posted the number. As for a production date to show it fits your car's production I don't know. I've got some extra rear ends out of the car, if I get home before dark I'll see what numbers I can find and take some pictures for you. If you can't come up with decent backing plates let me know, I should have some of those too. John

J-(Chicago)

The vista axle should work. Type O rearends have a 45 degree spline on the axles. Different than the 8.5" rearends although they are the same spline count.
If it's too long, you can trim it down, that's the joy of bolt in flanges.
Make sure you trim it safely and properly, and not with a sawzall. You want to retain the strength and not fatigue the metal.

J-(Chicago)

Another warning: Vista rears may have used a bigger bearing in the tubes, so you may have to press on the proper set.

2blu442

I just checked a loose type O rear end and on the yoke side of the pumpkin found what I believe to be the casting number that designates the year at about the 7:00 o'clock point. Then at the 10:00 o'clock is what I believe to be the date code. Three digits with the two screw heads cast into it like on intake manifolds. You'll have to check with one of the diff experts like Jim or Brian to make sure but this is what I suspect. I snapped a couple pic's if you have trouble locating them on your differential. John

jensenracing77

thanks, i will go check it.
is there a brand of bearings that are better than others? i still need to talk to the guy i am going to have rebuild it but i think he will know. he probably has them in stock.

507OLDS

There is a julian date on the front of the pumpkin,just behind the yoke,on the passnger side.That is when the pumpkin was cast,& that date will be 30-60 days before your car was built.Yes,your axle shaft is twisted,& I would not bother with that one.I have some spares,if you can't find one,but you need to find one from another 70 12-bolt O-axle,as they had the tapered roller bearing,with the outboard seal.The earlier rears had a sealed bearing design,& the shafts were machined differently for those bearings.The Vista rears will not work because they are thicker at the ends for a larger bearing.

jensenracing77

i just don't see the date. i got out the chassis manual and it tells where it is but my manual is for 71 and not 70. they are differant in 71. but now i know that this is one from before 1970 because it does not have taper bearings on the axle. looks like i will have to rebuild the one in the car and not this one. well i will rebuild both but this one will not go in my Rallye. i just hope the axles are good in the Rallye because it had a bad case of wheel hop the one and only time i took it to the drag strip. i let out of the throttle as fast as i could but still can't believe it did not break something.

2blu442

This is a type O rear end, I don't know for sure what year its from. But the top picture is a six digit number that I believe identifies the year. The bottom picture is the julian date that Brian mentioned. John

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507OLDS

Thanks for the visual reference.
I also have shafts with the RW507CR sealed bearing,that are good.

svnt442

Now that must be a coincidence.

jensenracing77

in your bottom picture, both of mine have the same number and one is the older style and the other is a 70. i will have to look at the other number. i sure missed that one.

svnt442

They probably kept the same casting for the center section and just re-tooled the tubes when they redesigned the axles and bearings.