I was running 11.35 with a 489 case in my 64 with the old 446". When we built the Dana I sold the 489. The 3.91 gears looked new yet with no wear. I was always told the 489 case was the good one. Now it goes 10.15 at 132 mph. What is that at a tad over 3600#? About 550 HP? stirthepot

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