When purchasing any vehicle with a "salvage" type title it is important to find out the exact type of salvage title the vehicle has.   In general salvage titles are sub-divided into "rebuildable" and "non-rebuildable" types.   A third type of salvage title called a "rebuilt or restored" title is issued to a vehicle that has been repaired, inspectd, and reregistered for use.    If you are purchasing a wrecked or otherwise insurance total damaged vehicle to rebuilt make certain the vehicles salvage title type is a rebuildable one.   Non rebuildable titles normally say non-registerable, parts-only, salvage certificate, certificate of destruction, or dismantler permit on them.   There is a caution to be aware of when purchasing a vehicles listed as having clear title with an insurance company assignment.  Most states will title these as "rebuilt" and not a clear title type when you take it to your DMV. 

The vast majority of states and Canada (will be all in 2010) are linked to the national vehicle title management information system.  By agreement a VIN number listed as destroyed in this system can never be registered again.  So if your looking at an eBay item with a certificate of desutruction, dismantler permint, or other non-repaiurable paperwork type do not buy it if you will need to use the original VIN number.  You can check if a VIN is listed as destroyed (non-registerable) or stolen for free at the national insurance crime bureau web site "nicb.org"