'08 Radio removal--bolts needed?

I just removed the radio from my Tacoma. It was quite easy, (except getting the dang clock/hazards out) as the last owner didn't bother to replace the bolts. I've had the truck for about 6 weeks, and hadn't noticed the radio moving or acting loose.
So-do I really need the bolts? And if so, what do I buy to replace them? I know they are 10mm, but how long? All four the same length?
BTW--Thanks to the thread started by Burgman back in '09, I was able to get the clock/hazard assembly out.

 

Try here

https://www.tacomaworld.com/threads/stock-stereo-mounting-bolt-size.220028/

Hope it helps

 

Thanks. Yes, that helps.