Andrew was born in 1942 or there abouts, making him 37 by the start of GFIII. Had he gone to the priesthood straight from school he would've been ordained in the late 60's, therefore Tom died in the mid 60's.
Tom: "They shot Sonny on the causeway...he's dead." Michael: "Turnbull is a good man" Shane MacGowan: "It was Christmas Eve babe, in the drunk tank"