So i have a 98 z24 lowered and i had alot of play in my control arm so i figured it was a bushing so saturday at work one of the techs helped me take it apart and it ended up the bushing was find but the treads on the bold were flat so i put in a bolt that i found in the shop that was the same but i am wondering if the bolt is supposed to be treaded the whole way?
In some cases no.
The subframe bolts have threaded areas that are flat for ease of finding the hole for easier threading.
It's been awhile since I've had my control arms off but if there is a flat area, there is a reason for it being there.
You can also look for the scoring of the nut that the bolts screw onto. If there is no scoring in the flat spots, then they're there for easier insertion into the nut.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO! 
