There is a 3:31 ring and pinion on ebay for a 12 bolt rear. I was considering a switch from my 3:07 non positraction to the 3:31 still non positraction. Is it just a matter of a professional doing the ring and pinion swap ?
What else would I need to go to positraction and if I don't race the car do I really need positraction ?
Thanks.

You can do the swap yourself but you are going to need a few specialzed tools like a press, & dial indicator & ALOT of patience. Used gears can be tricky to setup. A professional may charge $200-$300 to do the job for you. Do you really need positraction? Only you can answer that question.... there are several options avalable to make the switch: from changing the carrier to a posi unit or installing a lock-right in the carrier you have now.

Are these used gears?

There is a 3:31 ring and pinion on ebay for a 12 bolt rear. I was considering a switch from my 3:07 non positraction to the 3:31 still non positraction. Is it just a matter of a professional doing the ring and pinion swap ?
What else would I need to go to positraction and if I don't race the car do I really need positraction ?
Thanks.

A few questions...

1) If you don't think you need positraction, then WHY would you switch to a lower gear?

2) Do you realize you will probably notice Very LITTLE difference between the current 3.07s and the 3.31s? Coupled with the potential for a "bad" set of used gears, and IMO, it wouldn't be worth the $150+ it will cost to install (assuming you have a pro do it)...

Don't get me wrong, there will be a difference between the two ratios, but very minor... I will gain a little more accelaration, but probably barely quantifiable. Even moreso if you are driving the car without positraction and don't think its needed, then you probably aren't pushing the performance envelope...

Lets say on the freeway, you now cruise at 2500 RPM... With the 3.31s, your engine will now spin about 2700 RPM (at the same speed)...

IMO, 3.31 (or 3.42/3.55) are a good all around gear, BUT unless you need to replace the 3.07, or have the rearend rebuilt, probably not worth the effort and expense of the swap...


Now, IF you wanted to add a posi unit, it would be nice to possibly upgrade the ratio from the current 3.07s, and 3.31 wouldn't be a bad choice...

JMO


If you don't drive the car hard enough to spin the tires, then you probably don't need positraction... You don't need to "race" to need positraction. You just need to drive the car hard enough to spin the tires with non-positraction, to make the posi worth it...