im getting ready to hunt down an ecm for my 85. but when i look for 1 does all #s on it need to match or just the sequence of numbers in the first row after serv. no. ?would apprciate ant help i can get

Before replacing the ECM, attempt to reset it. Sometimes, that is all that is required. I don't know why it works, but sometimes it does.

However, if you decide to replace it, just take the unit to a parts store that specializes in GM parts and let them decide which one you need. Ask the parts guy to change out the PROM for you since it must be changed. My parts guy changed mine out in a couple of minutes and did not charge me anything for labor. The pins on the PROM are easily bent and the housing itself is easily warped, so be careful if you elect to do it yourself. Also, be aware that a spark from static electricity from you to the ECM will usually damage it. Before beginning the install process, discharge any static charge in your body by grounding yourself (touch a metal part of the body with your bare hand).

It's a pretty easy job. Good luck.