Break system boster . the part thats connected to the peadle has seal that is broken. i need to know the name of the part and how to replace it.

if it is in the brake peadle only you need to replace the rear drums/ rotors if you feel it in the streeing wheel it will be the front rotors

Sounds like the pitman arm. See #5 on diagram below. It has a ball joint with grease that is held in with a boot. It the boot is cracked open, you should replace the arm. You will need an alignment after replacing the arm. The arm does not contain any steering fluid, so if that is leaking, you have another seal broken somewhere...

if you have put in a boster or we call it a servo in uk it will need a complete bleeding of the break system to make sure all the air is out also make sure the vacume hoses are all conected as this is how it works from presure from the engine

The black box is an oil cooler for the engine. Its just a big o-ring sandwiched in between the flange and the oil filter. Should cost much more than 5 bucks for the o-ring.

The low pedal is for the most part, worn front pads

The check light and ABS is a System malfunction,
common is a Wheel Speed Sensor

Need codes, then diagnose.

Best bet is a repair shop

If you always work on your own vehicles, we may be able to
give some guideance

Remove the cover from under the dash and look up above the brake peadle about 5 inches you should be able to see the switch there may be 2 switches if you have cruse contronl. The brake light switch should have white and orange wires. just pull back on the switch to remove it. When putting the new one in push the brake peadle in then push the switch all the way in the hole then pull the brake peadle back till it stops this will push the switch back out some this will adjust the switch. Of course ckeck for proper operation. Here is a bad diagram of the switches but it the only one I could find.

replace the brake booster. the vacuum assist isnt working thats why its hard to push the brake pedal, check the booster and see if its leaking air.

U are going to need a new brake master cylinder, the internal seals are leaking and allowing the fluid pressure to leak down, this why the sinking pedal

If they work when the turn signals or the hazards are on then you need to replace the brake light switch on the brake pedal bracket.If the lights don,t work on hazards but do with the turn signals,then you have a fuse blown.If none of the above work then you need to check the wiring under the truck box for a bad plug in connection,corrosion or broken wires.

you will need to replace your master cyl and bleed your brakes
your master cyl is bypassing inside or the seal are bad inside the master cyl
there isnothing slse in the system that could cause this unless you are loosing fluid.
good luck