The following rack has been test-fit to the Delta and works great! Note that you will need the longer stays for it as well. The link for those is included:
https://www.amazon.com/Topeak-Explorer-Bicycle-Brake-Mounts/dp/B000FIAVHE/ref=sr_1_1?ie=UTF8&qid=1502914029&sr=8-1&keywords=topeak+explorer+disc
https://www.amazon.com/Topeak-Extra-Mounting-Explorer-Tourist/dp/B00QCKVQTQ/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1502914054&sr=1-1&keywords=topeak+bracket