70 Supreme Gear

70Supreme · 08-16-2003, 10:55 AM

Question:

I have a 1970 Cutlass Supreme with the "o" type 12 bolt differential & and a 2.60 gear. I want to increase that to a 3.42 gear with Posi. Is that possible with off the shelf parts? Anyone with some practical experience who would be willing to post some options, I would appreciate it.
Later upgrade will probably include a trans with overdrive.

Thank you

70ragtop · 08-18-2003, 06:37 PM

It's more likely that you have either the 2.56 or 2.78:1 rear as Olds did not use a 2.60 in 70. There is much debate about the "O" type rear ends. I am no expert in this arena, so I'll refer you here:

Try the Olds FAQ for more info: http://oldsjunction.classicoldsmobil...ential%20Codes

And contact Supercars Unlimited.

www.SuperCarsUnlimited.com

Supercars Unlimited
8029 A SW 17th
Portland, OR 97219
PH: (503) 244-8249
FX: (503) 244-9639

70Supreme · 08-19-2003, 04:24 AM

Thank you! I have found that confusion as well. It looks like I will need to count splines on my axel to confirm exactly what I can fit in the carrier or if I need a new carrier.

08-16-2003, 10:55 AM	#1 (permalink)
70Supreme Junior Member Join Date: Aug 2003 Location: Lebanon, TN Posts: 2	Question: I have a 1970 Cutlass Supreme with the "o" type 12 bolt differential & and a 2.60 gear. I want to increase that to a 3.42 gear with Posi. Is that possible with off the shelf parts? Anyone with some practical experience who would be willing to post some options, I would appreciate it. Later upgrade will probably include a trans with overdrive. Thank you __________________ John R. Reed Lebanon, TN 70 Old Cutlass Supreme

08-18-2003, 06:37 PM	#2 (permalink)
70ragtop Member Join Date: Dec 2001 Location: Dallas, Texas Posts: 32	It's more likely that you have either the 2.56 or 2.78:1 rear as Olds did not use a 2.60 in 70. There is much debate about the "O" type rear ends. I am no expert in this arena, so I'll refer you here: Try the Olds FAQ for more info: http://oldsjunction.classicoldsmobil...ential%20Codes And contact Supercars Unlimited. www.SuperCarsUnlimited.com Supercars Unlimited 8029 A SW 17th Portland, OR 97219 PH: (503) 244-8249 FX: (503) 244-9639 __________________ Jeff Herbert (70RagTop) Dallas TX 70 Cutlass Supreme Convertible 68 Cutlass S Convertible 72 Cutlass Supreme Hardtop

08-19-2003, 04:24 AM	#3 (permalink)
70Supreme Junior Member Join Date: Aug 2003 Location: Lebanon, TN Posts: 2	Thank you! I have found that confusion as well. It looks like I will need to count splines on my axel to confirm exactly what I can fit in the carrier or if I need a new carrier. __________________ John R. Reed Lebanon, TN 70 Old Cutlass Supreme

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