What master cylinder is this?

[brap999]

Hello, there is a late model master cylinder in my '63 c10. The previous owner has the cap tied and taped down, I'm guessing because it doesn't stay on so well anymore.

I wanted to replace it, but I'm not 100% what it is out of. Looking around it appears it may be an 80s - early 90's master cylinder from a GM truck. However there are two bolts with blue tips that extend out from the bottom driver side. I have no idea what these are for, and are not used on my truck. The replacement master cylinders do not have these.