i most likely will end up trying a custom suspension.i just wondered why marlin doesnt offer a 3 inch kit.it would make things alittle easier for inexperienced guys like me to have a kit available with set instructions and i am surprised that a 3 inch kit isnt in high demand,thats all.my concerns with custom suspensions is ending up with bad pinion angles, vibrations, uneven lift and mostly my lack of experience and spending more than the price of a kit to fix what i screw up .
Just buy the 4inch kit, it's all right there for you, it's the right parts and they have a world wide support group( IE US).. they will settle and you will like them I think.. Now if getting 3 inch's more tire clearance is all you want the just do a Body lift...A three inch body lift would leave your drive train and steerage/ Suspension stock. If you do that get replacement urethane body bushings to replace the old rubber ones. they will make the truck feel and handle good with lift.
THe rubber body bushings from the factory rot out over time, and crack/break and have to be replaced over the life of the truck anyways.. The Urethane ones will not rot or crack..They also remove road and engine vibrations so that the ride is smoother...