Welcome to PSN Mikefrfd,
Brakes, yes there is a vacuum pump driver’s side front engine belt drive, not uncommon for these to go out. Typically the dash “Brake” light will go on if you push the peddle to the floor and peddle “feel” will get hard then slowly soft.
Stage Two clutch I’m thinking is he has replaced the stock with an aftermarket and typically you’ll get more noise from them. For Syncros try using Redline MTL tranny fluid, it’s a great product and might extend the need for a rebuild, extended one of my trucks a couple years.
Knocky at idle, try changing engine oil brand. I used to use Delo 400 (which is great oil btw
) but a 4500 Miles when the oil broke down she’d idle poorly. Now use Rotella T5 with Donaldson DBL7405 oil filter and run to 5000 Miles and smooth all the time.
For the engine crank case vent turn the dog house on the driver’s valve cover 180 degrees, put on a 90 degree elbow and run your hose up and over the brake booster canister then down to inside the frame rail. Mine ends, such that I’ve tucked it into front of fuel tank skid plate. Make sure line has no uphills to trap any oil when you fasten it inside frame rail. The uphill to booster should keep most the oil drained back into VC vent.
Check the back of each head (where it faces firewall), there is a high pressure oil gallery plug in each end of respective head. It’s not uncommon for these to leak, Plug is like 2” in diameter and takes a 1/2” square drive to replace. Fire up engine get under truck with strong bright light and look for oil weeping out plug side.
We won’t hold it against you that you’re a mechanic... :) tons of great reading and good guys on here. Btw
love the Configuration of your rig.... ECSB 4x Dana front with ZF is one of my favs.