I e-mailed Ikelite to see if there was a possibility of an upgrade of my D70 housing to take a D80. My thinking was it would probably need a new back much like the D70 to D70 I-TTL upgrade. Ikelite's response is below.
"Thank you for the inquiry. I appreciate your interest in Ikelite products. Each Ikelite housing model is designed to accommodate a specific camera or camera series. It is not possible for Ikelite to modify your D70 housing to accommodate the D80 camera model. Therefore, you would need to purchase the appropriate new housing model 6808.1 to accommodate the new D80 camera selected. The most recent product and dealer information is presented on the Ikelite internet web site (http://www.ikelite.com)."
I thought if I could get a housing upgrade I'd go for the D80 if not I'll probably upgrade at the next generation so looks like I'll be buying a D90 or whatever Nikon produce next.
Ken