slimboyfat : There were certainly strong statements in the Watchtower against organ transplants, but I don’t know any concrete statement that it was a disfellowshipping offence.
There was no concrete statement that accepting an organ transplant was a disfellowshipping offence. But The Watchtower, 15 November 1967, p.702 did state :
That was sufficient for most Witnesses to believe that human organ transplants were contrary to God's will until 1980 when it was made clear it is a matter of conscience.Those who submit to [organ transplants] are thus living off the flesh of another human. That is cannibalistic. However, in allowing man to eat animal flesh Jehovah God did not grant permission for humans to try to perpetuate their lives by cannibalistically taking into their bodies human flesh, whether chewed or in the form of whole organs or body parts taken from others.