Rains current chassis she refers to simply as the Mk 2. All the numbers afterwards she doesn't pay attention to, they're just minor revision numbers that only have meaning to her mechanic. It's a vase type, just as the Mk 1 was. She greatly enjoyed her Mk 1 body, but it had reached the limits of its design in terms of begin upgraded. it was time for a fresh start. The Mk 2, while being an entirely new design, borrowed heavily from the lessons learned with the Mk 1. Rain knew exactly what she wanted and her body designer knew exactly how to give it to her.

While there are several dozen standardized bodies for second lifers like Rain, using readily available and interchangeable parts, she needed something more custom. While most second lifers have bodies with enough processing power to allow them to manage several hundred to a few thousand Virtual Intelligent (VI) worker robots, Rain needed something with enough built-in processing power to manage many tens of thousands of VIs. Most people arn't willing to live in such a body for an extended period. Rain decided to take it upon herself to be that person for her company.

It has actually worked out quite well for her. VIs that are managed primarily by the same person for an extended period of time become very competent at their tasks and are extremely valuable. By being that manager herself, she never has to worry about loosing them should they decide to move on to something else. It's also a much more casual working environment than upper management, working with her fellow employees who assist in managing her VI workforce. She enjoys it greatly.

The chassis for people like Rain, who decide to devote themselves to VI managing, are pretty much all completely custom designed. Cramming that much processing power into a body requires trade-offs and it's up to the individual it is being designed for to decide what those trade-offs are. Such one-off designs are very expensive, but very profitable long-term if a person sticks with it. For Rain, it has been especially so.

This SFW ref sheet was created by the extremely talented  dragonnetstorm

The original is here, https://www.furaffinity.net/view/28306626/