69 GTO, orig code WF 10 bolt, 3.23 open rear.

I like the ratio for cruising, but need a posi (don't we all?). My father-in-law's gear guy says he can add an Eaton posi unit to this rear for around $500. Sounds reasonable - has anyone else done this? Any recommendations on other types of add-on posi units?

Would I be ahead of the game to just spend more and put in a 12 bolt? I don't plan to race or abuse the drivetrain, but some occasional hard driving is necessary to cleanse the soul. If so, anyone happen to know where to find a reasonably priced 12 bolt posi between 3.08 and 3.36?

Thanks!


Chris

69 GTO, orig code WF 10 bolt, 3.23 open rear.

I like the ratio for cruising, but need a posi (don't we all?). My father-in-law's gear guy says he can add an Eaton posi unit to this rear for around $500. Sounds reasonable - has anyone else done this? Any recommendations on other types of add-on posi units?

Would I be ahead of the game to just spend more and put in a 12 bolt? I don't plan to race or abuse the drivetrain, but some occasional hard driving is necessary to cleanse the soul. If so, anyone happen to know where to find a reasonably priced 12 bolt posi between 3.08 and 3.36?

Thanks!


Chris

I did that to my 65 years ago. At that time I just went to the junk yard found one that would fit and swapped the case. I drove it for 5 more years. Probably should have checked 'runout' on the posi ring gear flange but didn't. Just what ever you buy try to find spare parts to have.I am swapping a 8.5 71 up rear now in my 67 Firebird. Why the 71, has better cruising gears as the 67 has 4.33's.The 8.5 is good and parts are available. 12 bolts are hard to find around here.

The following is from Jeg's website. I bought an Auburn Gear unit from them about 8 years ago and it's working great. My rear is a WH 3.55 so I used a different diff. Be sure to get a BOP 8.2" diff ... the Chevy 8.2 won't work. You will want to purchase an installation kit with new bearings and shims.

GM 8.2'' 10-Bolt NON ''C'' Lock, 28-Spline BOP Axle
109-5420113 3.36-Up, 28-Spline, 1964-71 $332.99
109-5420114 3.23-Lower, 28-Spline, 1964-71 $332.99

The rear in your car is an 8.2, if you want to put an 8.5 with 3.42 or 3.23 I have one available.