One of my favorite bass lines, love the run-out, too! I can listen to this over and over, and do.
I've been listening to the song in the car to get it down for our band, the bass really pops out of the mix, very cool.
I don't know if the distortion is intended, I would assume so, gives the bass some texture in the mix. Could be from the amp, tape saturation, a little of the kick mixed into the isolated track, a combination of them, etc. I'm just guessing here.