Needing to know where the fuel filter is located on a 1987 300E. Please be kinda specific. maybe even a link to a diagram would be helpful. Also appreciate any advice when changing it out. Thanks

Under the rear passenger side - adjacent the fuel filler. (LHD)
You need to get under the car.
There is a plastic cover that needs to be removed.
There are two electric fuel pumps, the fuel filter and the fuel accumulator.
The fuel filter is the fatter "silver" coloured unit. (or the same as the replacement unit you have bought).
Simple matter to change it out.
Don't forget to change the copper crush washers that come with the new filter.

If you get under the car don't forget to use ether ramps or solid stands. Use eye goggles to prevent fuel splash in your eyes.

Be sure to swap the plastic sleeve to the new fuel filter. If the existing sleeve is damaged replace it with a new one. Note, that the fuel filter and pumps are forward of the rear axle. The cover is black and secured with 3 black nylon 10mm nuts.

__________________
Fred Hoelzle

great advice. thanks all