Waveform, Think back to the Security Six and Speed six and Police Service Six days. That was Ruger's bread and butter (at least with security forces and police departments) they also had a following in the civilian carry department. Then ruger came up with a different way to do the internals and incorporated that in their new release of the Ruger Redhawk. That introduction must have been in the late 70's since in 81 at 21 my first handgun was a 44 Redhawk and they were still pretty new and hard to get. It had the same "case mouth edge" takedown abilities as their existing line of revolvers to its sub assemblies and was built like a tank. Much superior to the then famous S&W model 29 (ie. Dirty Harry). 29's have been beefed up since then, but at the time Ruger had it in the strength department.
The gun also had an interesting innovation in the interior in that just one spring formed the rolls of Trigger spring, Hammer spring, and trigger guard latch spring. This simplified the works and repair and possibly assembly time due to the fewer parts. Strength was and still is the Redhawk's strong suit and since it's introduction has been offered in a bunch of different models including short barreled one's, 4, 5, 6, versions for carry, and 7.5 inch models (some with rings included) for hunting. This gun comes with a standard usually found full profile grip frame and all were supplied with a square butt I believe (could be wrong on that last one). It also came in different calibers including 44 mag, 41 mag, 357 mag, and there might be others? Custom smiths would often take a 357 Redhawk and convert it to the 357 Bain and Davis which was a necked down 44 mag case to a 357 bore. It created quite the following and still is a great choice for a 44 mag handgun.
Then Ruger overhauled the Security Six series and all of its variants. Stock was built and sold never to be made again. It of course was replaced with what you're familiar with, the GP and SP series of guns. The internals were of similar Ruger design but with an obvious improvement in the cylinder lock up. The ejector rod was offset to allow a crane latch so the cylinder was held in place at both ends of the cylinder instead of the breech end and the end of the ejector rod as Smith's are. More meat was added and with the new lock up again, Ruger built a tank that will outlast many other makes of similar revolvers. Again these series were made available in several different barrel lengths, fixed or adjustable sights, and calibers. The other big change was in the grip frame area. No longer a full profile, it is now a grip stud if you will allowing an endless variety in grips. Trigger reach, grip thickness or thinness, and barrel angle could all be altered with different grips although Ruger offered them with only one. The former wood paneled version and now stock Hogue's.
Well with those series upgraded thought was then given to the Super Redhawk as an improvement over the Redhawk. All of the changes of the mid frame guns also occurred in the Super Redhawk, grip, crane latch, internals, etc. And of course more meat to handle larger pressures. Specifically viewed was the .454 Casull cartridge and a way for a six shot revolver to handle those pressures. They had already added as much metal to various areas that they could so looking for more they decided to extend the frame a couple of inches for weight and for a rock solid barrel/frame lockup. Offered in .454 and 44 mag for the 2.5" Alaskan and 7.5 and 9.5" Super Redhawks. Not as a replacement (since the Redhawk had such a large following) but in addition to. Barrel work on this guy is a bit tricky due to the long engagement and galling. Ruger uses and special anti galling paste to install these barrels and for the smith trying to do barrel work or shortening the longer barrels, this can become an issue. On the Alaskan due to its barrel length and extended frame, there's no barrel to grab onto, so any problems there have to be addressed by Ruger themselves. I haven't owned all of the above mentioned models in their variations, but far too many to admit to in front of my wife and I've come to appreciate the features of the later introductions of Super Redhawk, GP100 and SP101 and own some of each. Smithy.