i have a grill from wings west that i purchased when i bought my airdam. then i sold that truck and placed my 'noma front end on my SS. i did however have to cut out all of the factory bars that were inside the grill. i have heard of some that just zip-tie to oem plastic, but i couldnt tell you who makes them, and if they are available for the sonoma. i dont think they would be tho, and if they would, then you would still have to chop down the GMC logo so its even with the surrounding plastic. just go ahead and cut it out; its not very hard and the grill should slip right in. here is a pic of my setup:
Oh yeah and the billet I got was from Mr. Grille and it came with zip ties, I threw them out and made my own L brackets and bolted the thing in, I dont recommend that grill it was 60 bucks but it doesnt fit like more expensive ones.