All parcel codes locations:
1. You can find a parcel code in your cell in jail. (42318)
2. By the entrance of 110. (24252)
3. Chest behind house 2A in first heist (Forestside Resort). (99517)
4. In the kitchen in house 106. (77611)
5. In house 201, in the same closet as the safe with the watch is. (69999)
6. In a security booth in the second neighborhood, close to house 207 (53453)
7. At the park between 201 and 202. (68611)
8. In 202 at the ground level in a dresser is a parcel code (49637)
9. In 205 in the dining room, on a closet in the corner (54145)
10. In the park across 114 on a bench. (59444)
I think there is one in 114 hallway too but I already used it so I can't check if this is correct.