S5#sh run | b mls
mls qos map dscp-mutation Prob17 14 to 12
mls qos map dscp-mutation Prob17 28 to 26
mls qos


interface FastEthernet0/24
 switchport trunk encapsulation dot1q
 switchport mode trunk
 mls qos trust dscp
 mls qos dscp-mutation Prob17


for testing on R3:

R3#sh run | b class
class-map match-all dscp26
  match  dscp af31
class-map match-all dscp24
  match  dscp cs3
class-map match-all dscp28
  match  dscp af32

policy-map test
  class Prec1
  class dscp28
  class dscp26
  class dscp24

interface FastEthernet0/0
 ip address 180.40.7.129 255.255.255.224
 ip policy route-map Prob1
 duplex auto
 speed auto
 vrrp 71 ip 180.40.7.133
 vrrp 71 priority 111
 glbp 71 ip 180.40.7.134
 glbp 71 weighting 100 lower 90
 glbp 71 weighting track 3 decrement 50
 standby 71 ip 180.40.7.132
 standby 71 priority 150
 standby 71 preempt
 standby 71 track Serial1/2 51
 standby 71 track 2 decrement 61
 service-policy input test
!