kØemt's 6m/2m whip
I used a completely threaded 3/8"x24 TPI bolt with an Allen style head and a lock washer for mounting the cobalt steel heavy duty spring to the mount.
Next is a lock washer and a medium duty stainless steel spring.
Then a 3/8" x 3" extender topped with a barrel connector with locking nut.
A whip adapter with stainless steel whip tops it all off.
The radios in my truck are mounted on a "Shelf-it" brand over head shelf. I went with this brand because the fabric covering is actually fabric particles that are blown on to an adhesive coated aluminum shelf. (That way you don't rip all of the shelf material off when you are drilling holes!)