[sccc51106]

Hello, Do I need to get a different rear or can I change up to 3.73 with posi?
I have a 1976 t/a and am looking to upgrade. I've read all about the carriers and I still don't understand. Is it possable. What is the best way to go? I found a 79 rear with 3.42 gears for 300.00 shipped and I'm sure it needs a rebuild. What do you guys think. Thanks, Brad

[Tin Indians Rule]

Brad, I going to attempt to answer...but I'm sure there are more talented in this area than I. I've based this reading and asking questions. This may be completely wrong!!!

You basically have 3 types of carriers. Series 2, 3 and 4. Depending on your gear ratio you will have the series carrier that corresponds with your gearing. Example...
2:41 thru 3:08 requires a 2 series
3:23 thru 3:73 requires a 3 series
3:90 thru 4:56 requires a 4 series

These are not exact cut off's on the ratio's but give you an idea. I've never had to change a rear gear ratio except in a completely bare (no guts) rear end. But, I heard that you can use a spacer plate between the carrier and the ring gear that will allow you to run a 3:42 or 3:73 gear in a 2 series carrier. If your unit is currently in great shape I'd go that route based on what little I know. However, if your 30 year old posi unit is showing signs of trouble then replace it with a 3 series carrier and the gearing that you desire.