Greetings, I started this thread when I was looking at getting a ClicGear Cart.
If you follow the thread you will see that I ended up getting the ClicGear 3.5+. I think I included all the reasoning for that choice.
In my opinion... granted opinions are like buttholes everyone has one, you'd be crazy not to get the clicgear.
I just got a Sun Mountain C-130 bag as well (Christmas Gift from the family). You don't have to worry about it fitting on the cart. It fits perfectly fine. I haven't modified the bag or the cart and mine fits no trouble at all. Work great. I'll try to grab a picture to post.
I don't think anyone has answered his original question. Even Footjoys have different threads and thread patterns (eg fast twist, tour lock, pins, etc.) Figure that out first, and what kind of spikes you need. Then you can figure out how to remove the old ones and then replace with new.