OK, here goes....and I will try to keep this short and mostly related to the T3. There are two basic types of body construction options: Body-On-Frame and Unibody. Body-On-Frame as the name implies has a structural frame that carries most of the road, suspension, and engine loads. The frame is responsible for most of the energy absorption in a crash and defines the dynamic response of the car as well as most of the Noise, Vibration, and Harshness (NVH) characteristics of the vehicle. The body of the vehicle is generally isolated from the frame via rubber body mounts. Most trucks and some of the larger cars (Crown Victoria and Lincoln TownCar) are built this way today. Most cars built in the 1960's and early were built this way. Unibody construction has no structural frame. The body is generally made up of thin skins that are joined together to form structural sections and carry all of the road, suspension, and engine loads. The body is responsible for the strength and stiffness of the vehicle, the dynamic response of the vehicle and the NVH characteristics. Most modern cars are now constructed this way since it elimates redundant structures, produces a lighter body, and has better dynamic response. There is a third body construction type that is starting to find favor among the auto producers for low volume applications in particular and it is Spaceframe. A spaceframe vehicle has a skeleton of simple tubular members that define the strength and stiffness of the vehicle, its dynamic response, and its NVH. Non-structural panels (typically plastic or compsite) are used to close-out the frame and provide the styled appearance of the car. Some manufacturers are looking at structural panels to eliminate some material redundancies and to lighten the structures. So....how does all this relate to the T3. The T3 is definitely not a spaceframe. It is however a blend of body-on-frame and unibody, the T3 more so that the T1. The T1 is much closer to a body-on-frame since it is basically a driveable chassis (pan) that all of the suspension and engine loads are supported on. The body is simple bolted to it, although somewhat more rigidly than a typical body-on-frame. The T3 is closer to a unibody since the engine and rear suspension are tied directly to the body structure, at least in the late T3. the front suspension is not, however. So, we have a blend..... Enough of Vehicle Body Structures 101. Later, John Jaranson (that Ford guy again) '71 FI Auto Fasty http://hometown.aol.com/jaransonT3