I'm trying to figure out what year or years Ford had a factory turbo version of the 7.3 diesel, prior to the power Stroke diesel. I think it was only one or maybe two years? Possibly 1993??
I believe the 7.3IDI turbo was available in 93. 94 you could get the 7.3IDI turbo as a factory truck, previous it was dealer installed option (using factory parts). I'm not sure the first year this was an option, but I did have a work truck that was a dealer turbo 93.
Clux is correct in that 94 was the last year for the mechanical 7.3 (i.e. IDI) and he first year for the PowerStroke, all three were available.