https://www.bphobbies.com/view.asp?id=V450327
I use these plus some from HK. The BP Cheetah motors are sold by our local hobby shop which is very handy. I can peruse through the website for the details, then go to the hobby shop and pick one up. Very good quality and no problems with them.
Some of my bigger motors use those adapters. I havn't damaged one yet but I can see what you're saying.
Never tried the G Force motors.