Streamlined wingtip strobes.
There are a number of small improvements on my plane which distinguish the later, post 1979, models from most Vikings which were made in the 70's.
Fully retractable nose gear and cowl flaps.
The fully retracting nose gear is a mixed blessing. You go a little faster, but the penalty is mechanical complexity. The pilot has an additional parameter to manage, the cowl flaps, as well as having to maintain a complicated system of priority valves which open and close the nose gear doors in the proper sequence. When the priority valves, which are no longer manufactured, go bad the sequence gets messed up and the gear doors close, then the nose wheel comes up. Ouch.
Landing lights in the wheel cover.
The new style wheel cover with the landing lights built in is an upgrade done to my plane by Millers. You can just barely see the place in the left wing where the patch was scarfed into the old hole. These are the "160 mph gear doors." I make a real effort to be well below 140 when I drop the gear, the doors look like they must be subject to huge stresses even at low speeds.