What do you think...Bad trans, or bad converter?

Which do you think went south, the transmission or the converter (or both)? I was Racing yesterday in my final race before the division 3 finals (I made the team, so that’s good) and my transmission started slipping in high gear. First pass it went in to 3rd gear solid, RPM began to climb steady like normal, then it started to surge up and down 200-300 RPM. I lifted and aborted the run, got back to the pit at the only thing I could see wrong was the trans fluid level was ~ 0.5 quart low. So I topped it off and ran my second time run. This time there was no surge in high gear, but my RPM’s climbed WAY TOO high. I was doing 6800RPM at the stripe @ 105mph….I normally cross the line at ~6000 @ 112-114mph (4.10 gear, 28” tire….yeah, it was bad).

For those that don’t know, I’m launching the car in second gear (one of many things to slow the car down to run in sportsman). Looking at my time slips, 60’ and 330’ times look normal…1/8 mile times look close to normal (maybe 0.02 slow), but my mph is 2-3 mph low, 1000’ times are over a tenth off...the only pass I made under full power (second time run) it ran 12.25 @ 105. The early run incremental s said I should have run 12.00-12.01.

The trans was rebuilt about 7 years ago, so it is probably due…I’m thinking trans…what do you think? I do have a spare converter to try if needed, but I only have 4 weeks before the division finals so I need to get this fixed quickly….I’m pulling the trans either tonight or tomorrow.