Finally got a few moments to look this over and there is a signs of a leak around the boost unit at booth the firewall and at the connection between the Master Cylinder. I do not think it is leaking constantly. My suspicion is that it only leaks when I am doing a lot of breaking and hard turns like when we are backing the trailer into tight corners -- we have been doing a lot of that lately.
I see the parts on ebay for about $200 for ACDelco Unit. Any other recommendations?
I hate to break it to you, but if you are leaking where the master cylinder and hydroboost unit meet up, you most likely have an inner seal leak. Unfortunately this is fairly common when even the smallest amount of crud is pushed through the unit. The GM Mechanic's manual states that if you are leaking here, it's time for a new unit.
There are a few guys that will rebuild these though....but i heard it can be tough for the avg weekend guy that hasn't done it before.
My first hydroboost unit leaked and I was fortunate enough that AC Delco replaced it no problem with another brand new unit...but mine was <1yr old and brand new. A new AC Delco unit will run you $550 - $700; reman'd a little less. You can go ebay, but when it comes to brakes, I personally stick OEM and new.
On your hydro unit, there is a plastic disc covering a hole (it's near the top of the unit, faces the front of the truck), is it brown or blue? I noticed on my leaking unit there was brown oil behind the disc...on the new unit (that didn't leak), it was blue (color of disc) and there was no oil behind it. I always wondered if this was the way to tell if the unit was leaking.
