Gallien and Bennett are the returning players from the 2016 tournament, where NZ Heartland lost narrowly to Tasman and Northland, then defeated Southland in their last match in the second tier Michael Jones Trophy division.
"Dylan and Hamish got the experience at the competition and they performed really well last year. Mark was more than happy to have them back," said Lock.
While all 12 Heartland unions are again represented, as per the selection creed, the squad is heavily weighted towards the lower North Island provinces, due in part to Hurricanes Heartland actively playing at Under 19 level in the Central Region Shield.
Lock said by playing in that tournament, they were directly in front of the national selectors, rather than just looking through various resumes put forward by the Heartland unions.
"There wasn't a huge amount of nominations from the south. Whether that's because of guys going to the bigger unions, I'm not sure."
This year will also have a stronger buildup as the squad will assemble on September 7, a Thursday, before the opening game on September 10.
Previously, the players usually all met each other for the first time around 24 hours before kickoff.
"Heartland boys, they're pretty resilient, they won't go away. They'll keep coming," said Lock.
The opening game will be against whichever province finishes third in the Auckland Region qualifiers.
Hurricanes Heartland have their last game of the Central Region Shield against Hawke's Bay Under 19 on Saturday.