69 differential help

I have recently built a 350 for my chevelle and it sounds and feels strong but the gear in my car is killing it. I have the casting numbers off of the carrier housing which are 3969277NF and I have ran them in my chevrolet by the numbers book and it told me that it was a 68-69 chevelle 8.2" but this information was unverafied. I really need a gear but I don't know for sure if it is a 7.5,8.2, or 8.5 if anyone has any information on how to tell please let me know.
I have already looked for any identification "markings" like "triangle lugs" and "Fangs" sticking out of the bottom of the housing like the 7.5 and 8.5 and mine don't have either of these someone please help??????

It's either a 10 bolt or 12 bolt.
To tell which it is, is simple.
Look at the housing.....if it has a bolt at ther very bottom all by itself it's a 10 bolt.
If it has two bolts spaced equally from the center it's a 12 bolt.
With a 350 in the car it probably had 3.08 or 2.73 gears.

It is a 10 bolt I am sorry I should have said that to begin with I just don't know what size carrier I have wether or not it is a 8.2" or 8.5" I know it is a open diff. and it feels like a 2.73 or close to it is their a way of telling by the pinion nut? someone told me if it was 1 1/8" it's a 8.2 and if it is 1 1/4 then it is a 8.5 have any of you heard this before?

http://www.chevelles.com/years/69/69rearcodes.html
1969 axel codes.


http://www.reiderracing.com/

Check this web site and give them a call.

Look on the right axel tube there should be a code hand stamped that will tell you the gear set.

http://www.msa-1.com/custom/index.cfm?ID=34887

Here a book you can buy.


Hope this helps.

Jim