Here is my contribution.... if there is a javascript person out there to give some proper order to the script step, I think this will work...it is close - I have the SF RecordID stored in the related task record correlation ID-

(function execute(inputs, outputs) {

var requestObjTask = {};
requestObjTask.number = inputs.number.toString();
requestObjTask.correlation_id = inputs.correlation_id.toString();
requestObjTask.attachments = [];

//var attachmentData = {};
var grattach = new GlideRecord('sys_attachment');
grattach.addQuery('sys_id',inputs.sys_ids);
grattach.query();
if(grattach.next()){
//gs.log('flow if');
var sa = new GlideSysAttachment();
//gs.log('success1');
var binData = sa.getBytes(grattach);
//gs.log('success2');
var base64Data = GlideStringUtil.base64Encode(binData);
//gs.log('success3');
var attachmentData = {};
attachmentData.attachment = {};
attachmentData.attachment.filename = grattach.file_name.toString();
attachmentData.attachment.file= base64Data.toString(); // remove substring
requestObjTask.attachments.push(attachmentData);

}
// gs.log('reqobjtask'+JSON.stringify(requestObjTask));
outputs.ritmreqbody =JSON.stringify(requestObjTask);

})(inputs, outputs);