Due to emissions regulations, you cannot put an older engine into a newer vehicle/body. i.e. LBZ in a 2009 Suburban body (based on the VIN). If you had an 06 Suburban body, no problem putting an newer LMM or LML in - provided you can make it fit and communicate. I believe some states (Commiefornia) also require that the body/frame of the vehicle match the type of vehicle the donor engine originally came out of -- 3/4 ton for a duramax, for example.From what I understand...most builders and people try to install the engine appropriate w that year bodystyle....and I am not certain if it has do w the wiring and computer already in place so it will mate up and be able to communicate or not.
My suburban is lifted...they lift it a little and level it to that but I went w a 3 inch lift. That being said....I know some people want an OEM appearance or totally stealth so I feel like once the engine and driveline is installed they are lowered again to a factory like look.
The body lift is to accommodate the Allison trans. You could go the 4L85e route like the DuraVans, but need to tune the engine for lower power or you'll roast that trans.