[mickmate]

The 4000's use an aluminum casting with provision for a front mount as per the originals. They also need custom side plates for bearings and side mount plates (hangers). The original assembly is all expensive components. The AMP uses the Jag diff with a cage around it to fit original mounting points, these are available through a couple of sources. They all use the Dana 44 internals though some non Jag internals have different size holes for the crown wheel (ring gear). The non Jag stuff has a finer (stronger) spline for stub axles. They use splined dana spicer half shafts. I believe they have 1350 u-joints.