The mounting rail for the G36 carry handles should be universal, but I guess it'd depend on the make. I know all of the big-name, high-quality versions are cross-compatible, but I don't know much of SRC.
There should be one screw at the front of of the handle, and two at the rear. Take 'em out and the handle should slide off of a dove-tail style mount. That mount should be universal among G36s, so if yours is built that way, it should accept other brands of handles as well.
Note though that the mount isn't the same as a 20mm picatinny rail, so if you see that it's not, don't fret; it's supposed to be like that.