I think Bell Man should maybe stick to helicopter stories. Maybe he was thinking about Bells, not D-H's.
However, the US military did, and indeed does, still operate the Twin Otter as the UV-18A. They are currently used as jump ships at the Air Force academy, after a gentle life with the Alaska National Guard - and they were beautiful, low time, ships.
As a cautionary tale, some genius in the Guard, decided to run a replacement programme scenario, without ever considering funding the replacement for probably the best suited aircraft they could ever operate. As a result, the aircraft were grabbed by the academy, and the AK Guard got their replacement aircraft - the fabulous C-23B Sherpa (aka - the SHED). Just mentioning the loss of the Twotters to a guard pilot will make them cry!
Interesting side story on the fate of the US military twotter programme.
In 2000 a quick Reaction audit was requested by the USPFO on the transfer of 1.18 million dollars of UV-18 Fixed Wing aircraft parts to the Navy in exchange for the Navy's purchase and delivery of UH-60 helicopter fuel tanks. The various agreements negotiated and transfer actions taken, were performed outside normal operating procedures, without USPFO approval.
Agreements were not negotiated IAW DODI 4000.19 and NGR 5-2. Disposition procedures in AR 710-2 were not followed and a contracting officer was not used to obtain the Fuel tanks IAW the FAR.
The UV-18 parts were given to an agent of the Navy without following standard procedures, obtaining proper approvals, or using any documentation for the disposition. The UH-60 fuel tanks were also not certified by the Army as air worthy.
In one week the Navy's agent created a company, loaded the parts on a truck, sold $650K of the parts to a company in Canada, and purchased a new airplane with the proceeds.
As a result, the ARNG lost control and accountability for the parts, missed out on a reimbursable opportunity and created numerous legal issues that are currently being investigated by CID and DCIS. The final audit product provided investigators and command with a tool for focusing an investigation, addressing regulatory violations and avoiding similar situations in the future.