64 Cutlass rearend

I'm looking to purchase a '64 Olds F85 Cutlass in my area.  It has the 290 horse 330 and the two speed Jetaway automatic.  I've read that the standard rearend in that model would be a 3.08 10 bolt.  Is this a 8.2 inch 10 bolt?  Are these putting in a posi and better gears or should I ditch it? I know CC did an article on the 10 bolts a little while back and I've torn my house apart trying to find it but can't.

What you have is pretty much the base for the Cutlass bottom line up through at least '67, and I even think that was what was in my Sons '72 Cutlass S.  To answer your question directly, I really don't know how many inches in diameter the ring gear is.  The second part of your question I can say is that for a big block, I would probably ditch it rather than retrofit. 

We did a retrofit posi into my Sons '72 10 bolt, but the thing (with bearings and seal kits) came to a lofty $1400 when done by a reputable outfit.  Now, I can say it has been flogged pretty bad, and has never missed a day of service since it was done.  In fact the engine blew up before the differential let go, so I can't say much bad about the job that was done.  It seems like it was pretty stout - but it was behind a 350, and not a 455.

I am going to get one of the Mosure ready to use 12 bolts for my car - probably next year as I have already sunk a crapload of money into my Cutlass already.  I have enough to keep me busy for the short run.  They start (money wise) at around what we spent retrofitting my Sons 10 bolt.  So what would you rather have - a 10 bolt retrofit or 12 bolt turn key ready with your choice of gears?  For me the choice is easy.

Hope this helps - Bowser

Hey thanks for the info Bowser, and even though I'm on a super tight budget, I think I'm gonna try and spring the bucks for a 12 bolt.  I do have some good news though.  I talked to the owner of that '64 cutlass I wanted to buy today, and he wants 1500 for it.  Its only got 69000 original miles and has original paint.  If all goes well, there's going to be another Cutlass in our garage in the next week or two.

I HAVE A 64 LEMANS THAT HAD THE SAME REAR END IN IT.  BUT I THINK THE GEAR WAS A LITTLE HIGHER.  I LOOKED INTO BUILDING IT BUT THE BOP AXLES ARE RARE AND WITH THAT AND THE WEIRD DIFF IT WAS A LOT CHEAPER TO FIND A GOOD LIMITED SLIP FROM A 68 TO 72 A BODY. IT FIT RITE IN WITH NO PROBLEMS,  ITS ONE INCH WIDER OVER ALL SO YOU HAVE TO MAKE SURE YOU HAVE ENOUGH BACK SPACING ON YOUR RIMS.  BUT IF YOUR ON A BUDGET THIS MIGHT BE THE WAY TO GO,  YOU CAN STILL FIND A GOOD REAR END IN A YARD AND MOST PLACES ANYMORE DONT PAY ATTENTION TO WEATHER ITS A PERFORMANCE APLICATION OR NOT SO THE PRICE IS GOOD.  

My son has a factory 12 bolt posi in his 66 442, but they are going to be hard to find.  I agree with the idea of finding a later model 12 bolt posi.  Some internet sites list numbers to look for on the axel housings.  Typically they are stamped numbers on the front drivers side.  And I agree - they should bolt in with just a little attention paid to wheels and tires. 

He should be able to fit most any A body up through 1972 in there.  He may even find one off of a Pontiac, which wouldn't be really off base.  Many of the Olds posi units were Pontiacs because it wasn't until '66 (and don't quote me, but somewhere around that time) that Olds started making their own.  My full size Olds Starfire ('65) has a Pontiac posi in it and it came from the factory that way. 

If he picks up a used one, the oil should be changed out and refilled with the reccomended limited slip differential fluid.   

Have to go for now.

Bowser

After a week or so of trying to find the right parts for the right combo, I find out the car is not worth buying.  I stopped by the garage the car is at with my dad today and the Olds was on a lift.  Turns out, despite the low mileage and decent exterior, the bottom of the car was a mess.  Frame had loads of rot, trunk was a little rough, and the floors looked like they were ready to go.  It seems like this is the hundredth time something like this has happened to me in the past few months.  Oh well.  Theres a 70 or 71 monte carlo down the road that I'm going to look into next, God knows where'll that lead.