There is a page ref here serving 21 yrs
Alexander GOOD
Discharge date: 25 January 1873
Discharge rank: Serjt
Discharge corps: Dragoon Guards
The National Archives reference: WO121
also
Name:Alexander GOOD
Year of birth:1832
Place of birth:Daley, New Galloway, Kirkcudbrightshire
Regiment:6th (Or Carabineer) Reg Of Dn Guards
Discharged 1873 age 40, served Crimea, Turkey East Indies
He dies 4 Feb 1873, is this of any help as I see there is an Aug baptism in Ireland ?