the Pvi shocker was built for and distributed by smartparts, it was built by a company called Pnevensiors (spelling??). Smart part where looking for there own marker but wanted a low pressure, all electonic marker, this was the shocker, the original is the PVI but it was slow, heavy (i mean heavier than the shocker 4x4 brick) and unreliable and was a complete gas guzzler.
Smart parts then decide to bring the shocker in house and the 4x4 was launched a year or so later (around 1995/96), better reliability, faster but still a complete gas guzzler, i believe this is the shocker as most people remember (the brick shape) this has been modified over the years by smartparts and planet to bring it upto date, new boards (turbo board any one??), triggers, relaced the dome switch with the lever switch, vert feed instead of RH feed.
then we have the new 03 shocker, which appears to have solved a lot of the problems that exsited.
a brief history of the shocker
cheers
bruce