I have 2 sets of stock injectors. one set is out of my truck and the other set was in a head i just bought because mine had some small cracks. Anyway i bought new injectors and have to send a set back for cores, and was wonderin witch ones to keep? the ones out of my truck have a 820 printed on the injector tips and the ones from the head that i bought which came off a 2001 i believe have an 830 printed on the tips. Is there any difference, I dont know if the head i bought was an HO motor but it came from a truck with 60,000 on it. Thanks in adv.