Confirm ID for a 1st Gen Posi

[Patrick91914]

I've located what is claimed to be a '64 3.23 posi. It has numbers that read 1182316***42-13***G.M.C.**P

On a '65 Riv Posi, there is a flange with holes which mate upto the drive shaft. This posi, shown here:

http://www.flickr.com/photos/9179285@N02/3410093489/

doesn't appear to have the flange I'm talking about. Is this what the '64 posi units look like?

[RivNut]

The '64 chassis manual states the following:

"Disconnect rear universal joint by removing two U-bolts. (On 4700, mark flanged ball stud yoke and rear pinion flange for proper alignment at reassembly.)"

Looks to me like it's a posi out of an Electra or Wildcat.

Some pictures of a posi on a work bench show neither the u-joint nor the flange. I wonder if the flange from your peg-leg wouldn't bolt onto the posi you've found?

Ed

[Patrick91914]

Ed, thanks for the info.

I have a close-up photo that I'll post as soon as I can find my camera cable tomorrow. In any event, the photo does show two U-bolts. Are you saying that the manual indicates that the'64 Riv drive shaft mounts to the posi unit differently than '65?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RivNut</div><div class="ubbcode-body">The '64 chassis manual states the following:

"Disconnect rear universal joint by removing two U-bolts. (On 4700, mark flanged ball stud yoke and rear pinion flange for proper alignment at reassembly.)"

Looks to me like it's a posi out of an Electra or Wildcat.

Some pictures of a posi on a work bench show neither the u-joint nor the flange. I wonder if the flange from your peg-leg wouldn't bolt onto the posi you've found?

Ed </div></div>

[RivNut]

I'm saying that the Riviera driveshafts <span style="font-style: italic"><span style="font-weight: bold">mount</span></span> differently to the "pumpkin" than Electra, Wildcat, LeSabre "pumpkins" but the rear ends are the same. The flange part of your present 65 Riviera's "pumpkin" could be mounted on the 64 posi and you could use it. Once they had the "pumpkin" out of the rear axle housing, and took the u-joint and/or flange off the pinion shaft everything else is the same. This is based on what I read in the chassis manual and not from experience.

[Patrick91914]

Thanks Ed! This is good news and I feel a lot better now. The seller says it's out of a '64 Riv. I was just concerned about how to mate this to a '65 driveshaft.

[RivNut]

Patrick

Here's a picture of the rear end under my '64 Riv. It's "box stock." You can compare it to the picture of the posi that you have. To me it looks like there's a u-joint yoke on the pinion shaft in your picture where there's a flange bolted to the pinion shaft in this picture. I think the yoke and flange are interchangeable.

Ed

[1965rivgs]

The yokes will exchange but it takes a little expertise/experience to do it correctly. When this type of diff is assembled the yoke is tightened until a crush sleeve distorts putting a preload on the pinion bearings. On initial setup the preload is measured by rotating the yoke with a small torque wrench to a spcified resistance while tightening the yoke nut. In the field most techs just hammer on the nut a little at a time while checking the "feel" of the pinion for slight drag/resistance. If in doubt it may be wise to throw the diff in the trunk of your car and haul it off to a competent mechanic. The cost should be minimal. Good luck,

Tom Mooney

[Patrick91914]

Thanks Tom, I've found the correct yoke at Wheatbelt Buick. Will take your advice and have someone more knowledgeable than I to install. The unit is for my next 65 Riv.