I am a novice and am thinking about changing my control arms on my 66 Chevy Malibu to the Hotchkis adjustable ones. By going to the adjustable one will there be a need for Ball Joints? Also what are the benefits of switching adjustable?

Thanks

yes

Front or rear? Rear control arms don't have ball joints and Hothkis doesn't make an adjustable front arm.
There are several advantages to adjustable arms, correcting poor pinion angle is the most important. Most adjustable arms on the market also use solid ends or spherical bearings in place of bushings which is a huge step toward eliminating the bind associated with a converging link suspension design.

i too have been thinking of using the hotchkis adjustable rear control arms on my 71 elcamino, ive got bad wheel hop due to the bushings bieng shot im sure and since ill have all that junk out anyway why not replace more than just the bushings, maybe ill get a little more traction too.. since ive got none right now odds are fair..lol.. denny.. nice elky man, this is my 4th, i had a 69 and a 68 as my first 2 cars, if you come across a set of wheels in our area let me know, looking for as wide as possible out back and a bit narrower in the front, anything from 15" ralleys or cragar s/s's to billets.. im pretty open since the wheels i have now SUCK. hehe.. they are the old 5 oval hole mags.. ive never been a fan. if you get a chance shoot me an email too.. ive got a bunch of questions on the 5 speed tranny swap