First Gen Rear Axle Question

Hi everybody!

Likely a very dumb first question, but I've done a fair bit of searching and come up empty. I've got a 2000 V6 TRD 4x4 MT, and am in the process of trying to install a

$460 Viair 10007 VIAIR Constant Duty OBA Onboard Air System with 450C Air Compressor & 2.5 Gallon Tank, 12V Offroad Compressor, 150 PSI, up to 37" Tires

Viair 10007 kit. I'd hoped to mount the tank above the rear diff, as I've seen others do, but the linkage that comes off the rear passenger side of the axle housing interferes with the tank. It looks like this part simply isn't present on a lot of trucks, from the searching I've done. Its function isn't at all clear to me, what even does it do?



(Not my photo, but one from the internet that plainly shows the part I'm talking about.)

 

I'm fairly positive it's the Load sensing brake proportioning valve. It adjusts your rear braking power based on if you have a load in the bed.

 

yup, what he said.

 

That makes a lot of sense, it does appear to run into a manifold of sorts that the brake lines connect into. Neat, I had no idea that was a thing. Thanks!