While driving yesterday, my brake system started losing pressure, and hence I lost my brakes.  Once I got under the rig to take a look, I noticed the culprit is a cylindrical part that the brake lines connect to, which is located just in front of the gas tank.  There is one line going into this part, and one line coming out.

First, can anyone tell me what this part is, and what is it's function?

I was thinking about patching it until I can get it to my buddy's garage by replacing this cylindrical part with a piece of hose, or simply clamping off my rear brake line.  Before I do either of these though, I'd like to know what I'm getting into.

Any advice or info would be greatly appreciated.

Cheers

That part is the load sensing and proportioning valve (LSPV)
and reduces the pressure to the rear brakes to prevent rear
wheel lockup.

If it is leaking you might see if it can be repaired with some new
o-rings to stop the leak, otherwise it would need to be replaced.

It would be dangerous to drive the vehicle without it, should you
need to come to a quick stop, you might loose control with the
rear wheels skidding

Wild

my buddy popped by so I could take a look at the leak while someone else pushed the brakes.  Turns out it's a brake line that's leaking, and it was spraying onto the 'LSPV', which made it look like it was leaking.  now to replace the brake line.

thanks for the info

That might be easier, depends on where the leaking line is connected I suppose