Hello all you helpful people: I am installing a replacement crankshaft in my replacement 3000 block. I am wondering about the acceptable clearances on the main bearing journals. I intend to measure my clearances with plastiguage on existing standard bearings to see where I am before I order new bearings. I read that if you use undersize bearing liners one has to grind the crank journals? and then red blue color codes are a bit confusing! I am thinking that there are 50 year engines out there pushing specs on clearances that have never been touched and are working fine I gotta get within reason. Long and maybe confusing but any input will help.