2012 silverado differential change

[branedge]

my son blew his rear diff so we swapped it to a 3:72 from 3:43 now when it goes into 2nd it essentially slips out of gear i guess you'd say - rpm go up but won't go, if i let off the gas when RPMs come down it goes back to 1st and is fine (Reverse is also fine). i was told we needed to tune the TCM (and EBCM, not sure about this one) to set the correct gear ratio. we purchased the T2 platinum, can we make the necessary adjustments with this (or does it have to be custom) and think it will resolve our issue or was more damage done when differential blew?

thanks

[06MonteSS]

modify the preset canned ECM tune and change the gear ratio setting and reinstall the preset tune with that gear ratio change...