1. (related to an alignment and messing around with offset ball joints) Is it possible to replace JUST the lower ball joints without touching the uppers? yes both are new. It looks to me like you need to be able to fit the bearing press rod up through the upper housing spindle hole when doing the lowers....

2. Are there any issues with using offset ball joints in the lowers while leaving regular ball joints in the upper? (to improve caster) Wouldn't this pull the center link of the axle shafts slightly forward from the center line of the housing? Or instead is it best to put them in BOTH upper and lower positions, in opposite directions, to rotate but not move the knuckle relative to the housing.

 

Did BJ's last month in a 95. Did lower BJs first. So to answer your first question, yes you can do lower BJs w/o doing uppers.

In my shop I have done just lower or just upper offset BJs to slightly adjust caster. You get about a half a degree per joint (Moog does offer 1 degree joints - I have not used them). Do you know how much correction you need? If it's more than a degree, you may be able to accommodate the caster issue, but you will have other issues lurking in the weeds (bent parts, loose parts, worn parts maybe).

 

If your that far into it do both.