Gambhir carted KZN bowlers while under-pressure Test opener Wasim Jaffer does no good for his cause with another failure.
By contrast, Gambhir retired after belting the KZN bowlers to all the corners of the park. His innings was studded with eight boundary hits and two over it.
On day two of the two-day match against KZN Invitational XI, India declared at 271 for 6 to give its bowlers match practice.
Virender Sehwag hit a quick 40 and Rahul Dravid made 38 before retiring but VVS Laxman failed on a day when bad weather allowed for just 77 overs.
Sourav Ganguly hit an unbeaten 41 while Sachin Tendulkar was rested.
Brief Scores:India 271 for 6 decl (Gautam Gambhir 79 retd, Ganguly 41 n o, Sehwag 40, Dravid 38 retd, Kumble 23; L Frylinck 2 for 44, Mhlango 1 for 18, Pillay 1 for 65) Vs KwaZulu-Natal