Appreciate all the help and knowledge guys & gals!!
D4 7U4004 Right brake going to the floor and takes a few pumps while working the turning clutch before it'll stop the track, but it does eventually. Here's what i've done so far...

Missing both large drain plugs.  (anyone know what size & thread these are?) 
A fair amount of dirt and grime up in there, will need to be flushed out.

I pulled the inspection cover off under the seat and had a look, grimey but not rusty. Again, it looks like it could use a good flushing with kersene or diesel. Sent a bore probe down to have a look and it appears to all be in order. I can feel a fair amount of remaining brake lining so i'm guessing an adjustment is in order.

Found the top adjustment bolt and gave it a couple squirts of JB Blaster and let it sit for an hour or two. This is the question i have, hopefully not too novice of a query... (i'm a little gun-shy of twisting and beating on things i don't have experience with). I put a ratchet on the adjustment bolt and it's pretty darn tight. I double checked for a jam nut and couldn't find one, checked the service manual and there's no mention of a jam or locking nut. So... How tight are these bolts and how much force should i be applying to get it to move properly? Am i missing something here?

Thank you!

One of my adjusting bolts was snapped off so they can freeze up pretty solid--keep applying PB blaster , tap and keep working the bolt tightening and loosening be patient and it may break loose

Most prefer those drain plugs out unless working in deep water or mud. It lets any condensation and oil that leaks past the seals drain out. The other thing is to drill a 3/16 or so hole in the center of the plugs and put a cotter pin in. That will let it drain but keep rodents out. i do not know the plug size though.

Hi todsmith23,
The plug and gasket are available from Cat, the part numbers are,
Plug 0L0827
Gasket 0L1124

2 of each are required,

Regards

I thought that was the case, but I need the plugs so I can rinse out all the gunk....

note ithey are sae thread if your not in north america you need to specify sae thread. yes iwould get 2 sets so you have a spare set for flushing or wet conditions and a set you have drilled for a split pin so they drain and the split pin stops the wasps from blocking the drain hole. any good plumbing or fitting supplier will have suitable bungs.

its also a good idea to replace the special cast fill bowls on the rear of the trans case with plain bungs as the bowls are hard to get. especially if you work your machine in timber or scrub land as they do break easily(learnt from experience) just reverse onto timbers to raise the machine to the right angle and get the oil level.