Where do I find the serial and model number on a Cat engine that is on a 1988 Peterbilt tractor ?

look the block over good depending on which engine as to where the plates are . if the plates are gone you should be able to find the stamped ones . of course you could call the cat shop tell them which engine or a good decryption and they can tell you where it is . they do not like to sell parts with out a serial number .