Although I will be the first to admit I do not know everything, and learn something new every day, I must admit I have never heard of a torque converter destroying a thrust bearing in an engine before.
Torque converters are made of thick heavy steel, and fluid pressure inside of them is typically in the 200 psi range at most. Although i am sure they do swell a miniscule amount under pressure, in a normal installation there is much more clearance built into the assembly than the amount a converter can swell up. When a transmission is installed, you usually have to take your fingers or a small pry bar and actually move the converter forward about a half an inch to get the bolts that attach it to the flex plate started.
I am not aware of any kind of transmission bearing or other trans problem that would cause the torque converter to force the crankshaft forward and cause thrust bearing wear. If this were the case, it should be obvious to the installer during the assembly process, as it would affect the torque converter to flexplate clearance.
In my past experience (25 years, including internal engine repair) I have found the most common cause of thrust bearing failure on an automatic transmission engine to be incorrect service procedures such as hammering a harmonic balancer into place instead of using an installation tool to press it into place. (any of you other specialists who may have experienced something different, please feel free to post here).
I would be more concerned with the metallic noise you are hearing when the transmission shifts; this is definitely not a normal occurrence on a correctly functioning transmission. The first thing that occurs to me is a damaged or incorrectly assembled planetary gear assembly; if so, you will likely find some metal filings in the pan or filter if you drop it to investigate. Despite what your friend who rebuilt the transmission says, if he is unwilling to investigate and correct this for you, I would take the vehicle somewhere else (preferably to an established transmission specialist or your local dealer service dept) for an opinion. Noises almost always indicate something is wrong and should not be ignored.
I hope this is helpful to you, if so, an accept would be most appreciated! Thanks!
