I'm with @JBOMBER, there's almost always a few serviceable options around, so I wouldn't be looking to address a mature ruckman at the end of this season. TBC and Leuey are roughly the same age, both contracted until the end of next year, and not really capable of playing in the same team, so all we could offer a player from another club is a spot in a three way contest for first ruck duties. On top of which the only free agents this year are Clarke, Kreuzer and Spencer. No thanks.
I'd probably grab another ruck in the draft to develop alongside Draper (early, late, rookie, don't really care, just depends on what's available), and worry about who's our next first ruck at the end of next year.