Has anyone used Amsoil synthetic Transmission lube 75W-90 GL-4 in their 1969 4 speed?

First of all, I am not just assuming the failure of this 4-speed manual transmission was from the AMSOIL lubrication. I am saying this lubrication 100% caused the failure… This transmission was professional rebuilt to factory spec’s (With All New Parts) and had less then 1000 miles on the rebuild when a AMSOIL distributor at a local car show convinced me there was advantages of using AMSOIL and sold me this product. After the damage was done AMSOIL was not willing to stand behind their product! As I wrote before, rather then AMSOIL doing the right thing and repairing this transmission, AMSOIL spent more then twice the funds on testing of the oil sample to make themselves out to not be at fault.

I received the following comments from an AMSOIL supplier (I tell all of my customers that if there is a problem, I want to know about it immediately, because I'm there to help resolve any issues.) My reply to this person was if there has never been and issues with the AMSOIL products why would the suppler write this? (No Reply...)