As some of you may know i was gonna da over my Argo with HDI bearing set up. but went with the standard 2 seal flanges. would it be a good idea to update from old 2 seal flanges to HDI bearing set up as my bearings and flanges go? i would like some more info on them.....

1.what do you need to apply to keep water tight?
2.how long do they stay water tight for until they leak?
3.do the bearings last longer?
4.what would i need to do to modify my 1992 magnum for them?
5.i have an old style bearing extensions on the rear,do i need new ones?
6. i still have some older axles with no step at the end,would they still fit?