Good day all, I have a 1972 skylark with a 8.5 (cast lugs at 5 and 7 o'clock) that has a 2.56 gear set (checked gear part number). After reading many posts about 2 and 3 series housings (my stamping is pitted/rusted away) I want to ensure that I can upgrade this rear before I spend a bunch on parts. So My question is, If I am putting an eaton style locker in, with new gears and bearings, do I need to worry about it being a 2 or 3 series? Will the gears and unit physically fit in there fine? Thanks Michael
It's a good rear to upgrade, but your answer depends on what youre doing - if your using a Powertrax type drop in locker then you'd need to change the carrier to a "2.73- up" series or use a spacer (not recommended) if you wanted to change gear ratios to something more performance oriented. If you are just changing the entire posi unit, then just pick what you want to work with. There are many good Eaton style carriers available in the aftermarket for reasonable money, and just about any gearset you can think of..
You can put any gear ratio that you want into that housing. The ratios are 3:08,3:23,3:42,3:73,3:90,4:10,etc. US Gear was also making a 3:55 for this,but might be discontinued now. Any new posi unit forntjis will be a 3-series,and will work for all of those gears. If you are installing one of the inserts,like a PowerTrax,into your existing non-posi carrier,you would need a non-posi carrier from a 2:73-up. Since you are doing a complete rebuild,I would just buy a good posi unit like an Eaton,Yukon,or Tru Trac.