New hard drive in Mac Book Pro leading to occasional crashes and kernel panics
Try resetting NVRAM just to be safe. I do this whenever I service a MacBook.

Resetting NVRAM / PRAM
1. Shut down your Mac.
2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Turn on the computer.
4. Press and hold the Command-Option-P-R keys before the gray screen appears.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.

You may also want to make sure your RAM chips didn't dislodge when you dropped it. Here's how to find your RAM bank.

Hope this helps!