I bought the bead blasted variant for a 4" Barrel off of Brownells, The description said it was for an L-Frame revolver,
but when I got it in, I noticed the threads didn't match the original rods threads.
What's wrong?

Do the threads just look different, or will it not screw on?

They will not go in completely.

I'm not an expert but different year models use right or left hand threads

Make sure you have the extractor rod collar on when you screw them together. It takes up some space.

Mine screw in counterclock wise as the new models.

I had the entire cylinder/crane assembly assembled correctly.
Everything was in place.
The darn thing just won't screw all the way in.