From their quarterly filing it appears they are preparing to place an order soon. No model mentioned though I assume B777F & B747-8F would be prime candidates. Not sure whether they would go with the A388F but perhaps they could be a contender for the A332F?
"Our next step will be a significant investment in next-generation freighter technology, which we hope to announce shortly. We believe that we will provide a more compelling value proposition to our customers with leading edge freighter aircraft that possess better reliability, range, capacity, and fuel efficiency and improve our commercial-risk profile.
Any thoughts as to what models they would be considering? Possible 748-F candidate?