V6 coils on a V8?
You won't get three inches out of them, and they are probably a lower spring rate than V-8 springs, so, the truck won't ride as you think it should either. Not to mention that it will reduce your towing/load carrying capacity. Not a good plan me thinks.
The V-6 coils will fit but you will only net maybe an inch from them, go on ebay there is a couple people selling lift springs I would say 2.5inch coils biggest you can go before needing control arms and shocks







