Gen III PCMs - Small Block Chevy
From PartsWiki
The Powertrain Control Modules released to control Chevy's 3rd Generation Small Block V8 Engines
Identification
Gen III PCMs (like others) have a pair of identification numbers by which they can be differentiated.
Service Number
This is the top number on the label, abbreviated SERV. NO. on the printed label.
Hardware Number
This is the bottom number on the label, abbreviated HDW. NO. on the printed label.