Question does stall convertor rpm happen between shifts ?

Exactly. With the standard TF ratios of 2.45/1.45/1 the rpm drop could only be so much to begin with (%) and then what it actually does will vary as many have mentioned

View attachment 1716043528
mine was worse
After 1st Shift: 3,729 RPM. 40.82 % RPM Drop
After 2nd Shift: 4,345 RPM. 31.03 % RPM Drop
1st Gear is 63.95 MPH at 6300 RPM
2nd Gear is 108.05 MPH at 6300 RPM
3rd Gear is 156.68 MPH at 6300 RPM1