Mine does it in all gears when you romp on it hard. but thats because mine is rebuilt with heavy-duty internals and the transmission shop played around with it a lil bit
How many miles are on the truck..?
Has the transmission been serviced or replaced/repaired before?
Mine went out at 104k and my friend is at 114k and his is about to dump on him, so it may be time for a rebuild or replacement!
if its been serviced and was taken apart and cleaned, maybe the valve bodies are sticking, causing it to shift hard. sometimes when they take it apart and then put it back together, some things don't always work right, therefore returning you to the shop to have it looked at.