o.k., so I solved my problem. Went to Lowes and found the parts that I needed to be able to run mics on the Heavy Duty Flex Arm without having to buy a rapid adapter. Now the end with the tiny camera mount can lock into the clamp and the end with the 3/8 female threading can be used for mics. Below are the parts I used.
1) 3 inch 3/8-16 threaded rod (couldn't find any smaller)
2) 3/8-16 x 7/16 T-nut (makes a great platform for stereo bar)
3) 3/8-16 Locking nut (for stability at the base)
In action