I have a 1995 Chevy C1500 with a 4.3L engine and a manual 5spd. transmission. Recently I noticed one day that when I was in either 1st or 2nd gear and I really got on the gas or did a fast start my shift lever would kinda rock a bit to the right with the RPMs. Sometimes I can hear a small like knocking sound when I do a fast or hard start in 1st gear when I left off the gas to make a shift. I checked the rear transmission mount and its good and tight. I didn't really check the engine mounts because they are hidden behind the exhaust manifolds. From what I can see the engine is sitting correctly and not sagging to one side. When I hear the knocking sound it seems to be coming from the driver side so it seems like mabye the driver side engine mount is bad.Any ideas? Also if it is bad how hard would it be to replace.Thanks for your help all!