All,
I recently purchased a 1970 Olds Cutlass SX. My desire is to get it back to original. I have determined that I currently have a 3.23 limited slip differential. The factory had a 2.56, which helps, but I want to make sure I have what came with it. In the subject line, I typed in what the build sheet has for the differential. as stated, what does the line item "+G96 PLN AXLE 2.56" mean in English?

 

G96 was the RPO or option designation for the 2.56:1 axle ratio. PLN as in "Plains" gears as opposed to the "Performance" or mountain gears as such. AKA highway gears. The SX was conceptually the '70 versions of the "Turnpike Cruiser" that Olds started in '67. Not well embraced in its '67-'71 run, no matter what Olds called it. But the 2:56 gears made sense for what it was.

 

G96 = RPO code for Plains Axle Ratio 2.56:1 gears

 

Thanks. sounds as if any old o type 2.56 differential will do

 

I have a 1970 256 posi originally came out of my sx i will sell or trade plus$ for the 323 you have?

 

The lowest I ever find is 2.73...
2.56 is kind of rare. Should be great for economy, especially if used with the 2-bbl engine.

 

Octainia - a stock Q-Jet will out MPG a 2-bbl ANYTIME, if you keep your foot out of it!
Primaries are responsible - much smaller = better responce.
Been proven many times.

 

i believe the 256 rear was standard on 455 Supremes. And listed as an option on 442's

 

My 70 Supreme came with the 2.56 rear and a 350. It is still in the car with a 455 out front. Makes for nice cruising at low RPM.

Ted

 

True, but not so great off the line - even with a 455. Not sure why the 2:56 would be 'rare', it was the standard axle the SX came with. The standard engine was the L33 HC 455 2bbl. You could order up to a G95 (2.78:1) or G90 (3.08:1) at extra cost. The W32 engine (455 4bbl HC) was also an extra cost option that could be ordered into the Y79 package.

Even the Cutlass Supreme came standard with the 2.56:1 axle. BTW, the 2.73 was not offered in 1970. It was a 2.78 that was the next step up. 2.73:1 (G93 axle - code SA) was offered in 1971 and on.

 

Ha, it still puts you back in your seat....at 70MPH

 

Ted,
How or why would I argue with that? They were made to enjoy and it sounds like you're fulfilling that dream. I saw some pictures of the frame you got that cutout for the 72 S. Should have got the whole rear frame - it's in immaculate shape.

 

I know.........

 

Q-jet, '71 350 and 2.56 posi gives me 14.8 MPG mixed.