Necro-bump because this thread is a top hit for "d2-75 manual" and because I'm quite furious at Scribd, who charge $10 for download of the PDF (for which they clearly don't hold a copyright
D2-55, D2-75 workshop manual
also archive via Wayback Machine
D2-55, D2-75 operator's manual
If these links for the workshop manual ever become unavailable, I suggest a Google
search for "Workshop manual Group 20-23, 26, 30 D2-55, D2-75 filetype:pdf" - the filetype parameter ensures you get a link to the PDF of the manual, but the remainder appears to the actual title of the document, and including the "Group 20-23, 26, 30" seems to weed out spammers. There appear to be spammers putting up fake PDFs of obscure documents, for what reasons I won't speculate.