It's been 40 plus years since I had a drop out rear end in anything, so I haven't busted one up in at least that long, but when you did, did you notice the rough, coarse granular nature of the cast iron the case and the post unit or carrier was cast from? It looks like a low grade inferior grade of cast iron. 12 bolts were made of cast steel that had a much finer finished appearance,web caps and all.Of course, for serious racing, steel web caps and grade 8 Allen head bolts are the ticket, but as a preventative measure rather than an after failure fix. The way to improve the early rear end would be to cast up a far better center section with way better steel, then you could possibly move the center line of the pinion down and a bit further away from the ring gear in order to use 8.5" gears, and then the gasket surface of the carrier could be made a bit thicker in order to locate the center of the ring gear on the same center line of the axle shafts. It would be a rather big job, but it would essentially fix the problem. I don't feel that it's worth the effort when A body 12 bolt housings are being reproduced by the performance rear end companies again.