From memory of doing it on my '80 GLE V8 a few years ago;

Takt the vac line out of the booster by pulling and twisting it out of the rubber seal. Undo the two 17mm nuts holding the MC to the booster, then shift it forward off the mounting studs. No need to disconnect the brake lines. Slow work on one nut due to lack of space.

Inside it's hard to see and get at things, but you have to disconnect to top of the pedal arm from the booster pushrod (cotter pin or locking clip holding a pivot stud that comes out). Then remove four nuts (13mm, I think) holding the booster to the firewall.

The booster should now be free to wiggle forward, up and out.
--
Bruce Young,
940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified--and going to be crushed unless...)
New 144 from '67 to '78
Used '62 122 from '63 to '67