Here you will find a table of the Fuji 6x4.5 ( 56mm x 41.5mm, actually ) cameras produced over the years. I have listed "low" and "high" prices to give you a sense of what these cameras sell for in EXCELLENT, CLEAN CONDITION. If you are patient, you will find many of these models at the low end of the price range on ebay.com.
General thoughts on the early, mechanical Fuji's ( the "GS" models ) are that they have superb optics with very high contrast, so-so RF/VF, plastic-like bodies, and the durabilty of the GS645 75/3.4 model is a well known problem. The later models, (the "GA's" ) also get very high marks for their optics, have a more ergonomic design, more automated features, data impriting on film edges, and other fine features - however, many feel the AutoFocus accuracy is not in the league of 35mm AF Cameras. All Fuji 6x4.5 models accept 120 and 220 roll film.
Note: LENS WOBBLE. You may notice on the Zi, and other models, that if you GENTLY press the black retaining ring around the front lens element, there is a slight, yet clear "wobble" of the unit. The front lens element & retaining ring appear to "wiggle" or "float" in the lens barrel. When I first noticed this on my camera, I called Fuji repair...they had no clue what I was talking about...they said..."yeah, just send in the camera and we'll take a look..." After searching the net, I found this posting relating to the WOBBLE. Another reference is located here and here. And, after personally checking out six 645Zi models, it seems obvious this is a feature, not a flaw :>
Updated Version of GA645. 52mm Filter Thread. Takes 2 CR123A batteries. Closest Focus .7 meter. REVIEW & REVIEW(s)
75mm F 3.4 5 elements in 4 groups
Folding bellows camera. Frequently needs repair and/or bellows replacement. Original Lens hood is dedicated bayonet fit - runs $ 75-100 on ebay. Closest Focus 1 meter. Takes 2 LR44 batteries 6/84 issue of Modern Photography tested this lens. It is rumored that this camera was already discontinued by Fuji by 1985.