i have a set of 3 leaf pack 63's with the over load taken out in my 85 reg cab with a 3 in. block under them.  has worked great for years.  only complaint i have is when i have all my gear loaded in the bed and out on the trail, it's constantly bouncing off the bump stops.  without the gear, no problem, but when there is about 150 lbs or so of gear back there, its horrible.  anyone know of a good leaf to add to the pack to make it hold more weight?