69 4 speed hump measurement

I found this in thirty seconds. Also read the last post in the thread, it makes perfect sense to me.

http://www.forabodiesonly.com/mopar/showthread.php?t=166930&highlight=location+speed+hump

That's exactly what i did with my car, (the last post in that thread) and it worked perfectly.
One thing i should say is to watch when you are removing the floor piece at the transmission cross member and be careful not to cut into the cross member.
In my build thread i have some pics on how i did it too, but the above link is just as good.