If your original clips are too small, then you have the incorrect cable for your application. It may fit and function, but it wasn't made to exactly replace your part. Who made the part? Does both of your original clips not fit? What part number did you buy? Was there something that says you needed to slightly modify the cable mounts to accept the factory clips?
And, not for nothing because I've always had good luck with Mike's Montes, if a vendor is selling sh*t that everyone KNOWS doesn't actually fit their application, they should at least sell you the clips or tell you how to get it to fit. I mean, I can sell you a Cadillac shift cable that will clip in both ends, but it won't really fit. Same end result as you have now.