Up front Costello opts for the experience of Stephen Archer over John Ryan in the front row, while a return to fitness sees flanker David O'Callaghan preferred to Barry O'Mahony who is named on the bench.
The half-backs remain in place but Ivan Dineen gets moved from the wing to inside centre at the expense of JJ Hanrahan, while Denis Hurley fills the left wing berth occupied by Dineen so ably in the semi-final.
Friday's decider against Welsh side Cross Keys will be broadcast live on Sky Sports 2. Tickets for the game can be purchased here.
MUNSTER 'A' (v Cross Keys): Sean Scanlon; AN Other, Danny Barnes, Ivan Dineen, Denis Hurley; Scott Deasy, Duncan Williams; Dave Kilcoyne, Sean Henry, Stephen Archer, Brian Hayes, Ian Nagle, Billy Holland (capt), David O'Callaghan, Paddy Butler.
Replacements: Denis Fogarty, John Ryan, Barry O'Mahony, Brian O'Hara, Gerry Hurley, Declan Cusack, JJ Hanrahan.