ow i personally cant help you out but i done a bit of a search as the question is pretty vauge.. didnt mention what veichle its for as a start.. but i searched and am presuming its for a 91' vit?
gettin leaves to flex well takes a bit of work- the right springs [ most on the market are crap ], the right shocks [ most on the market are crap again ], and don't use nolethane on the main eyes- use original bonded rubber.
getting a spring over done right is hard. most of the ones i have seen just added hight and no more flex. the was a company doing 'kits' and these were shittfull! get a professional to do a propper spring over [ watch out for the so called ' pro's!'].
a coil conversion, well, even bigger grey area. this is one setup you don't want to get wrong. lots of fabbing and time and money and frustration. but when done right is freakin awesome.
this is a lwb sierra with a 3.5 litre quad cam all alloy v6 and toyata diffs. also with a custom vit body. the mounts have been fabbed to look factory and the whole chassis gussetted. the coil snouts are machined from a solid piece of aircraft grade alloy which bolts to the tower. these keep noise down and and are machined for a tight fit of the coil. if you want it engineered, use stock front arms with factory bushes, my engineer doesn't like nolethane like me and won't pass em.
this is the rear. once again custom made towers with alloy snouts and seats. fully triangulated rear for better flex and to keep the arms out of harms way. this also eliminates the need for a panhard rod. as you can see alot of time has been taken with every mount and weld. this vehicle was submitted in writting before it was approved, and so far so good. if you want to be happy with something take the time and money to do it right, and it will last, and the cops will also give you credit![ yes it does happen]. and if you don't have the budget for custom stuff, just get aftermarket springs and some lockers, you will still have a ball.
if you want it done right dont do it on the cheap IMHO..
