what makes xreas difficult to replace is that the opposing corners are connected with hydraulic fluid. the fluid gets moderated through an actuator mounted to the frame at about midpoint of the vehicle. the actuator does not tie into the electrical system and no lights will illuminate if xreas is not functioning properly or you remove it. you generally cannot replace a single shock if there's a substantive leak because you cannot add fluid to the system - that is why you replace in opposing pairs and the entire line which comes already with fluid. if you only notice slight misting early on and no leaks you can get away with replacing only one shock because they come slightly over filled from the factory

there are pintle valves at each corner that can be used to allow for the removal of a shock without fluid leaking all over the place. look up an xreas removal video to see. if you do it wrong though and fluid leaks out you are screwed and need to replace the whole line. it looks like from your post too much fluid has been lost and the line itself from FL to RR is needing to be replaced along with the shocks. the reason everyone gets rid of the xreas is because it's costly to replace but there is nothing wrong with the system itself. replacing an xreas line is not something I'd attempt unless I was very sure I knew what I was doing (again, if you try this yourself and you mess up you cannot add fluid, you have to buy a new part or line). I have xreas and do like it so I understand where you're coming from in not wanting to remove it

Deniseh, factory X-Reas fairly easy to replace and check valves right the at the connection. I did my both front ones while ago @ $250 each and those worked fine for six more years and now one of the new ones started leaking. These are $350 now and I didn't want to put in more money in product that fails routinely (don't ask me about front brake calipers because I can go on whole day). Also I realized that each time leaky strut looses fluid it can not be refilled. Long story short: I've Bilstein 5100 now on all 4 corners and those work perfectly. Minimal body roll at speed and fairly soft on bumpy roads. If I have done it sooner I would save myself $500. I dont miss my X-REAS.

Does anyone know where I can find the Bilstein B6 4600 shock set for my 2015 4Runner Ltd?
Looking to replace the XREAS system and not looking to lift.

I've learned that the 5100s are good but result in a significantly stiffer ride. I'm mostly a daily city driver but do some limited off roading

I can't find the 4600s anywhere. Any advice/assistance would be appreciated.

Thanks

It's been 2-3 months since you asked question. I just got 4600 from rockauto with great price. You can try it. Rockauto is little hard to do search, it is using some old ancient internet tech. But their parts are decent priced.