i cracked a brake line on my 84 4wd pickup right by the gas tank. i went to take a brake line off of one of my parts trucks and noticed it had only one line. the 84 has two lines and some weird lookin cylinder thing behind the gas tank on the frame rail, what is that thing? is it necessary for a wheelin rig? i would like to just bypass it with the simple system thats on the parts truck but i dont know what it is, any info would be great.
thanks.
edit: also the cylinder lookin thing has a steel rod that goes down and attaches to the rear axle.

 

LSPV (Load Sensing Proportioning Valve)????? Not to sure thou

 

it's not necessary, but as you can see, there's a line from the front brake circuit that you'd have to plug if you don't reinstall everything.

and the pic is wrong- the front line is not a return. it gets pressure from the front brakes.

 

ok cool ill just swap the system from the parts truck over thanks guys