Tom Rains, with all due respect, Although I agree in using manual mode... you are not really answering his question. You don't spend $400 on a flash for iTTL and just accept the under or over exposure that is occuring. We don't even have enough information about the situation he is taking the pictures in. Are they during the daytime?, dusk or night? Is he using fill in flash mode, or full... That would make a difference. Does he have his camera set on Program with slow sync during daytime or not. There are simply too many variables.
On the other hand, Tom Dyszkiewicz, in order to get a qualified answer... you need to be more descriptive with the problem you are having, and provide us with more specifics so as not to get a general answer.
One cannot solve a problem unless analyzed carefully. The D70 is capable of and does expose correctly. In most instances, it is human error that produces poor exposure. That's why one must practice, check, practice, check, and on and on....
Paul