anyone know what these are for??

[k20gmc]

1984 3/4 4x4. the brake line runs to this then out to wheels. cant figure out what its for?  bolted to frame and rearend. striping frame and sandblasting it. figured i would ask before i go all chuck norris on it! bahahah.

[bd]

Height-sensing [load] proportioning valve.  Scroll through this link for more info...

http://forum.73-87chevytrucks.com/smforum/index.php/topic,16967.0.html

[k20gmc]

 looks like a headache to me . think ill rip it out, lines are all rotted anyway. thank you very much!!

[Avidyn]

I've had to deal with those a bunch on 80's Toyota trucks. PITA to take care of when you want to lift them. If you don't get the height right, the rear brakes lock up when they're not supposed to. Or, they don't have enough pressure on them. You can rip them out, but you'll probably want to run a replacement valve somewhere in line. You won't get the right balance if you don't. Good luck!

[Blazin]

Pretty much useless. Only there for idiots that don't have a clue how to drive.
When you have a load in the back of the truck you don't have as much weight on the front axle, hence the front brakes are easier to lock up.

[bake74]

looks like a headache to me . think ill rip it out, lines are all rotted anyway. thank you very much!!

      Unless you plan to haul extremely heavy loads or a heavy trailer all the time, you wont need them.