Custom may refer to dealer's options/upgrades, or those installed by an owner. For example, GT had their base model Dyno cruiser as well as a deluxe, and some special named models; they may have had different features over the few years.
I believe that fenders were not normally furnished with the base model GT Dyno Glide (1" uni-fork); the internally geared hub (multiple speeds) would be another option/upgrade, that I can see. Deluxe models had fenders, as well as a springer fork, but were also single-speed. Seat looks to be a replacement; closer matching Velo seats are available (~$40?). Later Deluxe models, like that tri-color also shown, also may have had pleated seats and moto-grips as deluxe features.
The two-tone black/white may be an older model, the pictures do hot show the front of the head tube very well (decal or aluminum badge). The two-tone grips also suggest an earlier (relative) make, ~97(?).
Custom (sic) may also simply refer to the GT Dyno Kustom Kruiser, as shown in GT Dyno Kustom Kruisers Katalogs of ~20 years ago (with sensational spelling).
A multi-speed model with fenders may command a greater price; other plusses - some people prefer non-red rims and low-maintenance painted forks.
