34311161859 1990 BMW IX alternative for Brake Master cylinder?

[95BMWIC]

May have a Brake Master cylinder issue on my IX - not getting any fluid from the the rear port

I see these are a bit on the expensive side.

Is there anyway that a regular one from a E30 could be fitted - or better question hat is the difference between the IX Brake master cylinder and the IX? The angle of the output?

Is there a rebuild kit available? Has anyone tried to rebuild one?

[packratbimmer]

It is possible to get them apart, but I wonder about kit availability. The clip can be tricky at the end and there might be a central locking device of some kind.