2004.5 lly Suncoast stage 4 kit in the trans and a precision 2400 stall converter . Trans build was over 10yrs ago. Ran the truck at the track, went 12.3 on tune 3, turned it up to tune 4 and limped it on 4-5 upshift I believe, cleared a P0700 code, backed up in the pits went back to make another pass and while lining up I realized reverse was gone and it actually moves forward in neutral. Went to leave the track and it limped again right outside the gates driving very easy. Code P0777 this time. Cleared code again and still no reverse and it moves forward in neutral. Any advice? Or troubleshooting i can do to figure out what’s broken? Thanks.