>did they make a Borg warner 3 speed? and if so how strong was it

There were several Borg Warner 3 speeds put into cars. The strength depends on the model and application. The strongest was the heavy duty T-16. In the 60's it was used in high performance GM applications when the optional 4 speed was not specified. They're fairly rare though, since most high performance buyers opted for the 4 speed.

Bob