RE:looking for brake master cylinder for 91 850i e31 UPDATE, NEED HELP ON PENTOSIN

[anovaso]

Thanks ross1 , yes the car is beautiful, thank you. Looks like the car was featured on another post last month, another guy went to look at it before I did and hesitated to buy it but I ended up with it after just seeing it once! Car looks amazing just standing still! But still it's time to get it back together and drive it.
I am not a newbie by any means to wrenching and have worked on still work on all my bmws, e24, e30, e21, e23, e34 and now my e31 is a whole new but beautiful beast.
This is where I am at now and I need some help or direction as there is a lot of different information on this forum about these early e31's.
1. I have the replacement used ABS hydraulic unit and the old unit that came with the car, both out of the car. Do I use Pentosin 7.1 or Pentosin 11s to refill this system and install new used ABS hydraulic unit, where do I fill and bleed this system from and is there a certain process or anything else to look for when doing this? The reason I mention different Pentonsin versions is that when I look up info on this abs system, some say that both power steering and ABS use pentosin but do they share the fluids? Online the power steering shows it uses pentosin 11s? Or are these two system separate from each other,and the brake power booster and abs connected?

2. I just ordered the Brake master cylinder from Oreilly's, my buddy's friend is a manager at a local oreilly's and is ordering the master cylinder shown on their
system and at an awesome price of $94.99. Do I just use regular but good quality Brake fluid? I do have some Prestone Synthetic Brake fluid, is that ok?
Clutch master cylinder is untouched and clutch seems to work fine when i start the car and go through the gears. I am ordering the used brake fluid reservoir/expansion tank and cap from another used part source online as i write this.

3. My car shows it has ASC and DSC and is a 6 speed, so some forum post and info on the internet say that the 6 speeds indeed have ASC +T for traction control. How do i know for sure that it does or not? And the biggest questions about the ASC and DSC, info I find on these systems say they are electronically controlled systems. So does that mean they do not have any direct hydraulic relationship to my abs or power steering Pentosin systems? Or are they electronically controlled hydraulic systems?
There is just so much info out there and I want to be sure I have everything correct when putting everything back together.I am not penny pinching at this point. This car deserves to be put back together correctly and I am going to that and I know this car cost money to maintain correctly as well, not a problem.
Thanks for any info or direction. Tony

[PabloRock]

I know this is kind of old, but did you get a brake master cylinder for an e31 for $95? I am replacing mine as we speak and ended up getting an e32 cylinder for $188. It's supposed to fit the same but is a mm smaller (the e31 version is $600+). Also, synthetic dot 4 is what to use (so your prestone should be fine).