2.3L to 5.0L swap need help

You can use the factory 7.5 assembly for quite sometime. If you decide to change to an 8.8, you will need the whole rear end assembly. I did my 4 to 5.0 swap two years ago and it took quite a bit of time, sweat, blood, and money to get it all going. It would be best to get a donor car so you can have the wiring, computer, brake components, fuel lines, rear axle assembly, and any other extra components you might want to save.
 
There is ALOT of things different. The whole harness, shocks, struts, springs, rear end, steering rack, spindles, sway bars, gauges cluster (tach..it doesnt work on a 5.0 and it only reads to 6k instead of 7k), fuel lines, brakes, some of the brake lines and god knows how much other little ****. Alot of things are the same though like the k-member, control arms etc.