No codes, which is driving me crazy

so i just discovered that my engine vin does not match my transmission vin...could this be the cause of some of my issues? and i have no idea what happened, used truck, it was fine until the diff blew.

sorry should have searched that. Dataviewer 2 (now to see if i can understand it!)

is there any way for me to read the log files that i recorded on my tuner?

My son blew the rear end out of his truck so we replaced the 3:42 with a 3:73. Afterwards it wouldn't shift into 2nd (seems to drop out of gear). We were told gears being out of sync was the issue. So he bought the T2 platinum so we could change the gear ratio.

We've done this but not it shifting ...

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 ...