[cd66malibu]

Hi guys,
I've got a '66 with a 10-bolt open rear end with 3:73 ratio.(Not real sure about the ratio...but I like it.) I also have an early 70's 10-bolt posi rear end out of a Laguna S-3 with 2:73 ratio.My question is: is it possible to take the posi unit out and put it in the open rear end, keeping the same gears already in there? (I don't want to put the Laguna rear in 'cause of the 2:73 gears and the extra 1" width of the rear end.)Or, am I better off just selling both units and buying a posi rear that fits? Thanks for any help, Chris

 

[Derek69SS]

I'm not 100% sure, but I think all 10-bolts after '72 were 8.5" and the earlier ones were 8.2". I don't believe the posi is interchangable. Someone correct me if I'm wrong.

In the 80s there was also a weaker one on S-10s and Camaros, I think 7.625", but that doesn't apply to this question in any way

 

[BlueSS454]

To put it simply, you can't use it even it were the same diameter ring gear. There are 2 different carrier sizes, the 2 series and the 3 series. The 3 series is used on the 3.73 rear and the 2 is used on the 2.73 rear. The Laguna rear will not fit in the 66 anyways. I tired to put a rear out of a 77 Malibu under my 70 while I was building it just to roll it around but it just didn't bolt up.
Not that this has any relevance here but, the 78-88 G bodies had a 7.5" rear in it which was the weakest thing GM ever put out. The G body 442s, MC SS, and GN's did have an 8.5" rear however. Now that rear can take some abuse.

 

[chev65elleSS]

First you need to find out if there the exact same type of rearends. It's either a 8.5 or an 8.2 ring gear diameter, here's a good website to identify GM 10 bolts just by looking at them. I'm not sure, this site may have the carrier size and series.

GM 10 bolt identification (Try later, it's not working right now, sorry)

If there not the same you can't make the swap. You can also just go with a Powertrax unit(both worlds, a Locker and a Limited Slip), if you like your gears. The Powertrax goes into open differencials.

 

[big gear head]

The '66 has a 8.2 10 bolt and the Laguna has a 8.5 10 bolt. The parts will not interchange between these rear ends. The Laguna rear end will not fit in the '66 either. As for the differential series, the 8.2 uses a 3 series up to the 3.08 gear, but the 8.5 uses a 3 series up to the 2.73. Each rear end is different. The 7.5 10 bolt uses a 3 series up to the 3.23 gear, but the 3.08 goes on a 2 series.

You just need to get a new Eaton posi for the 8.2.

 

[cd66malibu]

Hey guys,
Thanks for the info on the rear ends. (sorry I took so long to reply but my computers been having problems) Looks like I'll be putting the laguna rear up for sale and getting an Eaton posi unit. Thanks for all your advice big gear head.
Chris