Good-day Ozzy,
Machine shops will cost you an hour of time in set up alone.
These should do the trick.
E-Z LOK Corporation - Thread Inserts part # 319-4  Thin Wall  Internal thread 1/4Â-20, External Thread 3/8Â-16
Call us and we will be happy to answer all of your questions and provide you a solution.
Robert
Star Sound Technologies, LLC
Machine shops will cost you an hour of time in set up alone.
These should do the trick.
E-Z LOK Corporation - Thread Inserts part # 319-4  Thin Wall  Internal thread 1/4Â-20, External Thread 3/8Â-16
Call us and we will be happy to answer all of your questions and provide you a solution.
Robert
Star Sound Technologies, LLC