This is a 6.2L 6L90 swapped 1972 Monte Carlo. The build was done by someone else about 95% complete. They brought it to me and I'm trying to figure out why the transmission doesn't want to shift. All the codes are gone except for the brake switch. I know this has come up before and I understand how to correct this issue.

my main concern is if the OS is compatible. I was told the car originally had a 6L80 in it and then they swapped in a 6L90. Supposedly the ECM and TCM were updated, but their lack of knowledge and inability to relay the correct information to me hasn't left e with much to work with.

Can someone please take a look at this tune and let me know if there's any compatibility issues that could cause any shifting issues?



Chase Monte Carlo - 8-27-21.hpt