whats the width of these 8.8 axles? im going to replace it with a ford 9".....

 

Why swap in a 9"? Its not really all that much stronger than the 8.8. The ring gears are about the same, the only real strength advantage is going to be the pinion support. Keep in mind that if you do this swap you're going to have 2 different bolt patterns on your truck. You're also going to have to swap the 9" over to disc brakes or you might end up with something screwing up in the ABS system. Also have you figured out how you're going to run the VSS sensor on the 9" that is on the 8.8. You're going to be doing alot more swapping and fabbing on this swap and you're going to gain not much strength issues.

 

Parts for the 8.8 are plentiful, it's a strong proven unit and many peole have years of experience servicing them. The 9.75 does not offer that much more support and part choices are scarce. If heat is an issue get a mag-hytec pan. The 8.8 can stand up to Cobra abuse and has a decent girdle strength. The weakest point is the C clips which can be eliminated for $120.