BDBENZ - I am not sure about the dates. I think that all 87 models have the problem of potential faulty B2 pistons. On the 126 like yours, there is sufficient room to get to the piston w/o removing the tranny. I have heard it can be a DIYer job with the 126.
My mechanic said that the B2 usually fails while driving in traffic/around town as the constant shifting up/down causes the faulty piston to fail.