Later axles have a simple banjo bolt with a pipe running off.
Some older ball bearing type (? Ive never taken one apart just squirted with plusgas) have been converted, many using push fit connections, the pipes can run anywhere, engine bay/side of the tub....it's just a matter of poking around and seeing what you've got and taking it apart enough to be sure the air can get out as it expands but won't suck water under rapid cooling