I have the 2.77 posi out of a 88 iroc... which is what i drive.... it is going bad... makes a horrible eheneheneheee sound(or something like that) around the corners under acceleration. lots of people tell me it it is spider gears and that it would be cheaper to just replace the entire rearend.... i found a 3.27 posi out of a 87 iroc( has 100,000 miles or so).... for $475 plus i have to give them mine.... do you think this is a good deal.... and if i do this swap... what about my speedo?