Your location would be helpful when looking for big parts like a rear axle housing. I have a rear from a 69 located in NC. How about posting some pictures of your 69 Stage1 convertible. Here is your original post http://www.v8buick.com/index.php?threads/resto-1969-400-stage1-conv.281669/
I've got this I guess it's called an 8.25, out of a 68 GS with original 390 GM gears, posi, spyders need replacing tho. It is clean, in Mich.