Im trying to see what are some lenders that FedEx and UPS uses. Do I have to look into which investment bank the two firms use to issue stock to figure this out? I'm confused...

Issuing stock makes someone an owner, not a lender. "Lenders" create payables on the books, not stock. i.e. financing is divided into debt (borrowing, lenders) and equity (ownership).

If they are a big lender, they may be listed in the disclosure notes of their statements. Do you have a copy of their statements and you just needed to know where to find it? Or are you doing this totally from scratch and need to find the statements?

Yes all the above I guess I can go to their website and find the statements and now I need to know where to look once I find it.

Comprehensive Search Page

If you can't find any info about a company's debt elsewhere, looking at the annual statement gives you the info you are looking for. Many times they will have it in footnotes or in notes at the end of the report. They usually write 'See Note ##'