Suburban transmission

I have a 1995 suburban with 260,000 miles. Six months ago, one cold morning, on my way to work, the auto transmission clunked at every shift. I dropped it off at a local transmission shop. They tested it all day and could find nothing wrong. I drove it that PM and the clunking was gone. Yesterday and this morning it happened again. It doesn’t happen in the PM. I had thr trans fluid cahnged 7-8 months ago. Any thoughts would be greatly appreciated! Thanks. John

Try leaving the Suburban overnight so they can test it in the morning when it is cold. The last time I had a hard to diagnose problem, I asked my mechanic to drive it home a couple days until the problem occured again. It worked.

Is this the original transmission? If so, it is probably due for an overhaul or a replacement.