Blue_Thunder

iTrader: (1)

I just bought a 1990 10 bolt posi with 2.73s. I want to rebuild the rear end. I bought the 1990 because I know it has 28 spline axles, Wanted to upgrade from my stock 86 open diff. My question is what ring gear size will it have or does that not matter. I am looking at this right now http://store.summitracing.com/partde...5&autoview=sku

I have a limited budget so I can't spend $500 on a carrier, This car is just going to be a street car anyway.
Any input would be great.

Wow, I just realized the part I listed is not the whole carrier, oops. What 3.73 carrier is out there for under $500?

big gear head

What you need is a gear set that will fit the differential that you have. There are special thick gears made for the 7.5 10 bolt that will allow you to install a 3.73 gear on a 2 series differential. You can install one of these on the posi that is in the 2.73 rear end that you already have.

BluFBdy

iTrader: (1)

to be safe id pull the axles out and count the splines, you shouldnt trust word of mouth when it comes to parts, not only that but did you open it up and see what shape its in?

Blue_Thunder

iTrader: (1)

The 86 Rear End is whining right now. I have already payed for the 1990 10 bolt. I thought GM switched to 28 spline in late 1989. I am not gonna use the 2.73 posi. I have 2.73 gears in my 86 right now-its just an open diff. If the posi is still good in the 1990 I will use that and just get new gears in it.

BluFBdy

iTrader: (1)

im in the same boat, but i picked up an 82 saginaw rear with and eaton grenade-lock and 3.73 gears, i just advise that you visually inspect the carrier, i brought mine home and the spider gears are all chipped and messed up, there is no way im going to use it now.

Remember that if the rear had 2.73 posi it should be a series 2 carrier, meaning you can only use a certain numeric range of ring/pinion setups, series 3 has like 3.23 and up which is what i just got.

As far as the changeover im not sure because i think ive got a 26 spline axle but then again i havent pulled one to look yet

Blue_Thunder

iTrader: (1)

So since the 1990 rear end is a series 2 I can't put 3 series parts in it? I Thought series 2 and 3 were interchangable.
So when I am looking up ring and pinion setups I am looking for ones that are series 2 then right?

http://store.summitracing.com/partde...217+4294776352

And would this truetrack work
http://www.jegs.com/i/Detroit+Locker...2A317/10002/-1#

big gear head

If you get the thick gears you can install them on the 2 series. These gears are made just for that reason. The 7.5 is the only rear end that I know of that has 3 series gears available for the 2 series differential. The 2 series is made for 3.08 to 2.41 gears. The 3 series starts at 3.23. The thick 3.73 gears will fit the 2 series. There are probably other ratios available for the 2 series too.

Blue_Thunder

iTrader: (1)

http://store.summitracing.com/partde...217+4294776352 This is the summit 14-0041 3.73 gm 10 bolt gear combo kit for a 2 series.

big gear head

That should do it.