Hmmmm... I have to take issue with the TREMEC book. I can't figure out where they got the 336 figure. Using more conventional math methods with the numbers above (wheel diameter X pi, converted to feet per minute X gear ratio, etc, etc.) I come up with 3119 rpm @ 70 mph. When I figure it back the other way (1996 rpm/ 4.11 X tire circumference, etc, etc.) it comes out 44.8 mph.

I can post the rather lengthy process I used if anybody is interested. Meantime, can somebody else do the calculations and see which is correct?