No where. In 71 the tallest 9 3/8 was a 3.42. Back in 68 they did offer a 3.91 option for a different rear than a 71. Now the gear set might interchange but you would have to ask Roger OPH. I suspect they are chicken lips. My understanding is there are no aftermarket sets made either.
no, at last look there are NO aftermarket gear sets for 9 3/8" or 8 7/8" ring gear rear ends. you can, however, find an 8 1/2" rear end assembly which will bolt right into your car and for which there are a nigh infinite number of ratios available. :Smarty: http://www.v8buick.com/showthread.php?t=75045
Good luck getting that 8 1/2 to last under a boattail with some numerically high gears in it. Why exactly is 3.42 to little gear for you?
Thanks. The truth is, I have had so much trouble finding good trim parts for this car at reasonable prices, I have decided to gear up this car and drag race the old car. I have a built 455 in it with headers and a lot of engine and transmission mods. It should run strong. Thanks for asking. Ed