Converter / Trans Slippage

[uptime]

How do you diagnose whether your trans or converter is slipping (or both)? I am getting around 15% slippage based on my rpm, tire diameter and gear ratio at the finish line. The car is a 3400lb 68 Camaro with a mild BB, TH400, 4.10, 3000 10" converter, and 29 x 10 tires. My trap speeds are between 110 and 113 mph and et's in the 11.90's. I am crossing the line at about 6,100 rpm.

Thanks in advance for any input.

[John_Heard]

If it was the trans, normally there won't be any question if it's slipping or not. It will normally be very evident when you shift. You could pull the dipstick and smell the fluid, if it smells burnt there might be an issue but I think you're probably seeing converter slippage. 15% is not out of line for a looser converter.