I may be entirely wrong, but I can't imagine there are any "original" ANYTHING out there, anymore. As far as I know, most of the original strains that are now legendary, disappeared before any kind of concentrated effort to maintain and stabilize anything. By the time anyone got to that point, most of the stuff was crossed with this and that or something or another. But, NOW, the complexity of the hybrid lines is so long, there isn't anything that can possibly stay the same as it was, originally. When I started smoking, in the 70's, everything was from outdoor-grown landrace stuff -mostly sativa from South of the border. A lot of it was poorly-grown with no visible trichomes....They lacked a lot -by today's standards- of what weed is supposed to look like, but what those old strains had was distinctive smells and flavors. You knew when you had the skunky blueberry weed that came from Mexico. You absolutely knew when you were smoking Columbian. You absolutely knew what That weed tasted like. There really weren't any well-known strains, back then by comparison to today.
As far as who has the real Sour Diesel or any other hybrid....? Who knows? Personally, I think a lot of these strains are here for awhile, but then they disappear, within a few years -through their own complex lineage and integration with every other strain out there. If anyone was maintaining them, then someone would know it. I don't even know if it's possible to maintain cuts for decades. And if you weren't around to know what they are supposed to be to begin with, then anyone can tell you anything about what the strains are...and how would you know, one way or another? For example, I was around when Thai weed was around, but what people are calling/selling Thai weed, now, isn't even remotely the Thai weed I know...not even close. Same thing goes for Columbian...I know what it's supposed to be...but when someone sells it, now, it's not the same thing. That's why every operation needs to have some employees who are old and who can still remember what weed used to be. Otherwise, it's just all going to end up as meaningless hype.
I mean there are probably still some tasty strains out there, but they appear and disappear like waves on the ocean. I think Sour Diesel is probably one of them by now.