NikonWeb published a very interesting interview with Kodak's lead engineer James McGarvey on the early Nikon-based Kodak DCS cameras:
Q: The Electro-Optic Camera - the World's first DSLR - was designed and constructed for a US government client. The customer preferred Canon cameras, so you built it around a Canon F-1 body. Later, when you decided to make your first commercial model, you used a Nikon F3 body instead. Why?
A: Nikon and Canon were close competitors and either was a viable choice for a professional digital camera. The Canon preference was specific to that first customer, but the US Gov't. customers more often preferred Nikon, so we used the F3 body on the Hawkeye II cameras, before the DCS. For the DCS, the choice was also simple, as newspaper photographers were the expected prime market and Nikon held a solid lead there, at least in the US. I believe we thought that Canon might have a slight edge in Europe, but we expected to sell more systems in the US initially.
Q: Did you in any way cooperate with Nikon on the development of the Kodak DCS? Was Nikon even aware of your project?
A: No and no. I believe they were surprised when we announced the DCS. We bought F3's through normal dealers (I don't remember who), and since the quantity was small before the product launch, I doubt if Nikon was alerted to anything ahead of time. I remember that we were packing the F3 back door in the kit with the DCS, since we had it and a user might want to use the body with film at some point. Nikon told us we couldn't do that as we were not an authorized dealer. We could incorporate the F3 in our product, of course, but not "resell" cameras! Generally, though, I believe Nikon was happy with the situation, since they were selling F3's and the first commercial digital camera was carrying their lens mount. I don't remember any complaint other than the door issue.