Interchangeability

[Belgium Cuda]

Is a 8 3/4 axle housing from a Charger and a GTX of the same length? Why I ask is that I want to put the -742 from the Charger on the GTX wich has a -489 but the driveaxles from the GTX/489 are longer and thicker. Or could I use the longer driveaxles with the -742 and the same (GTX) housing?
A lot of questions but I am eager to learn and the -489 unit has a lot to much play, it's painful to put the car in gear. 

[hemiken]

The center chunks will interchange in to each of the housings you have but keep the axles together with each housing they came out of.  Everything should bolt back together by changing centers only.

[Chryco Psycho]

the same year Charger & GTX will have the same length housing & axles but there are  3 different lenghts for the Charger & 2 for the GTX depending on the year
 the axles will be the same spline & will work with the swapped gear set 

[Belgium Cuda]

The Charger is a -68 and the GTX a -69, the driveaxles from the GTX -489 is approx 1/2" longer. Is it the suregrip type that
decides the length of the axles?

[hemiken]

The center has nothing to do with the length of an axle.

All centers are interchangable with each other wether they are a 741 case or a 742 case or a 489 case and they can be an open center or a posi center and non of wich matters for interchangabilty.  Only thing that will differ in some cases is the Yokes as they come in different sizes and lengths.  Just a case of changing out your tailshaft to suit