Hello I am looking into the WW SRC308 guns. They have exact features that I want however, I am confused on hand guard compatibility. Do they use DPMS High handguards? Or is it a different thread pitch?

They simply use mid-length handguards.

If you want to add a rail, it "should" simply take DPMS high models.

When they first came out with the railed model and the ability to buy just the rail on the WW website, you could cross reference the "WW" rail part number to the Midwest Industries equivalent and I think they even had the MI markings on them.  Later, the rails were marked WW or Windham Weaponry.  I don't know if that means they contracted with MI to make their rails with WW markings, or if WW started making their own rails.  But I doubt WW would go through the trouble of changing the pattern just so they could put their own name on the rails.