I have the opertunity (sp) to buy a 89 4X4 sub for $1500. Its in good shape,its black & gray so paints coming off in spots. But anyway,the
engine knocks when it starts up,but when it warms up its not that
noticeable. If I do buy it, what would cause this & how long can I
drive it like that ? How much damage are we talking about?

 

350's are tough man. A buddy of mine had a 88 that started knocking pretty great after 100k ROUGH MILES! He pretty much tried to blow it up everytime he drove it and it kept on taking the abuse. 50k miles later it knocked so bad the truck would shake and it would still bang the rev limiter. He sold it last year for $1200 with gear oil, stp oil treatment, and bar and chain lube (just for fun) in it to hide the knock a little bit... I could never do that to someone, but it does make a good story from time to time.