I was wondering WTH you were talking about covers, I've done a ball joint axle before and there are no covers, just ball joints, snap rings, castle nuts, typical BJ stuff... When I did my king pin axle I did the whole shebang. Worthwhile for peace of mind. Lower bearings get nasty when not regularly greased, king pin will rust and then chew up the cone. Cone wears and spring gets weak and allows play causing death wobble. The bigger the tires the more risk and you may have to preload/shim the spring a bit to keep the tire under control. Having dealt with death wobble before I don't mess around with front axle stuff. If I'm in there and componenets are unknown age or service history it all gets replaced.
Anyhow that lower cap can be a bear to remove. Lots of heat cycles, PB blaster and a BFH will get it loose. They are usually a bit stubborn.
When I did mine I used
this kit ... Though when I did mine they were $49 per side instead of about twice that now.
Wow, and the
spindle bearing/seal kit was $13 when I did mine, now $31.27.
Going by D60 parts prices inflation is a lot more than the alleged 3% as this was only 5 years ago... Maybe better prices elsewhere but 5 years ago 4wdfactory.com had the lowest prices I could find on this stuff, a bit less than local stores and easier to just order everything I need online and not have to deal with parts jockeys who don't know a set of points from a king pin.