I was just finishing up replacing my CV axle, but I can't figure out how to tighten down the steering knuckle/lower control arm nut. It's a bolt on a ball bearing, apparently...it keeps spinning when I try. I used needlenose pliers to hold it a bit, but one can only do that for so long before either stripping the bolt, or getting too tight to grip.

Anybody have any advice on how to finish up this project?

If you can somehow clamp the ball joint, the fitting is tapered and if you can press it hard enough, it'll stay still. try maybe a C clamp or a valve spring compressor.

whack that bitch with a hammer and try to seat it. dont hit the threaded side, hit the other side. if you can get it seated well enough, you wont have to use a clamp.

So...basically reverse the pitman-arm puller idea...sounds like it's definitely worth a try! Thanks, I'll give it a shot tomorrow.