The little sensor at the block is a KNOCK SENSOR..That retards the Timing..
The black box is a Secondary intake shorter/bypass for better bottom end and midrange

FWIW I never took off the Intake MANIFOLD when I did Headgaskits on the 104 motor AND SAVED LOTs of TIME (Just moved it over)
I could do a 104 headgaskit in under four hours..
I WAS Doing LOTS of them when The 300E E 320 were under Warranty They PAID GREAT! 9/10 hours