2nd gear slipping, no 4th

1999 Suburban, 262k miles. Trans supposedly rebuilt at 135k.

The other day in a parking lot I noticed my truck revving in 2nd rather than accelerating.

You never feel it shift into second. It feels like 1st holds fine until suddenly it flares in rpm, then it does an awkward shift into 3rd.

Never even attempts 4th now.

My guess is that it's cooked and needs rebuilt.