As a graduation gift (University of Michigan MBA) to myself and my Bullitt I decided I needed to upgrade one of my untouched aspects of the car the drivetrain. So a Ford Performance one piece aluminum driveshaft and an Eaton Truetrac differential were ordered and installed (twice for the diff, shimming sucks). The Ford Performance driveshaft is a pretty easy install and took about 3 hours. It clearly reduces a significant amount of weight off of the stock 2 piece steel driveshaft but more importantly for me it got rid of much of the play in the drivetrain which caused clanking noises on hard acceleration and jerking about at low speed idle (the car has Ford Racings Hot Rod Cams which lope at idle). A few simple hand tools and a jack and jack stands make it an easy enough install if your ok laying on the garage floor for a few hours, a lift would be a lot more convenient. The Eaton Truetrac on the other hand is a lot more difficult to install especially on my car which runs a watts link which is in the way. It took me the better part of a day to get it all done. About an hour and a half to get the diff out (highly recommend using a magnet to get the axle c clips out). A press is needed to get the ring gear off the stock diff and a press to get the new bearings onto the new diff, this required me driving to a friends house. Installation is a pain, as my new diff required different shimming than the stock one. This is an exercise in trial and error along with patience to get it shimmed right along with some creativity to get the right combination of shims. This requires a dial gauge devices to check backlash, I also recommend a friend to hold the driveshaft in place. Haven't gotten to give the diff a good workout, will get some autox runs in saturday. This brings the total weight of the car down to about 3255 with a half tank, meaning even with me in the car its close to 100 lbs lighter than stock.