I know in the old days there was no test for the converter and many engines wer'e distroyed, Is there a test or someway to tell if its bad or going bad these days? have a friend who lost his engine in older GM truck. He was lucky even ou t of warrentey the General replaced his engine. Thanks in advance

 

Most modern cars will give you a warning either in the form of a 'catalyst' light on the dash or a diagnostic code. As far as testing, a vacuum test or backpressure test can be performed. Either test will confirm or rule out the presence of a plugged converter. I have those tests somewhere in my notes but if you google 'catalytic converter testing' the same tests I'm referring to should come up.