I'm looking at putting a 4" suspension kit on my truck. I've looked at kits and they start around 809 for a block rear end kit but I've also looked on eBay and think I can price my own together for around 400. Will it make a difference if its all different brands. And if i by a 4" leafs upfront will a 4" block in the rear will it keep it leavel or do I need to go 5" up front to get a true 4" kit.