I have a 98 Expy that makes a popping noise when the temp is turned to full cold or full hot. This appears to be the problem I have.
By reading all these threads, this seems to be a common problem with our trucks. Can't Ford redisign the darn thing so this doesn't happen anymore? It looks like all you would have to do is put a small metal sleeve over the end of the shaft to prevent it from spreading if it were to crack.
My wife is not going to be happy when she finds out how long she's gonna be without a truck to get this fixed.