Well finally after 345,000 miles the master cylinder finally gave out on the 89 740. So today was my fix it day after getting a new MC ($160). It took me 4 hours to do the total job which required removal of all 4 wheels and replacing the rear brake hoses. Then the bleeding and putting everything back together. This is a pretty straight forward job and is a 1 man operation if you have a bleeder .

 

where did you buy the master cylinder?

 

Got it on line from "Parts Geek LLC" and it was the complete new ATE MC with new plastic container. I checked the price and with shipping it came to $176. When I sucked the old brake fluid out of the old MC it was black because of the deteriorating rubber in the MC. I flushed the total system with new fluid.