To answer your question, the regulars for the 1981 Expos were:
C: Gary Carter (bobby Ramos as the main backup)
1B: Warren Cromartie
2B: Rodney Scott
3B: Larry Parrish
SS: Chris Speier
OF: Andre Dawson and Tim Raines were regular starters. Other guys who got a lot of playing time included Cromartie, Jerry White, Tim Wallach, Terry Francona, Ellis Valnetine and Roland Office - the third OF spot was a bit of a revolving door.
SP: Bill Gullickson, Steve Rogers, Scott Sanderson, Ray burris, Charlie Lea.
RP: Woodie fryman, Elias Sosa, Jeff Reardon, Bill Lee, Stan Bahnsen.