500GB Shows as 385GB..where did the rest go?

Hello mvp and welcome. To be blunt most drives do not have the available space they advertise or state they have but your does seem to have more unavailable than I would have expected.
The other thing I am curious to is why format it FAT 32 and not NTFS??

The only thing I can think of is that there is an inordinate amount of drive manufacturer software on it - much the same as you get with some USB sticks. In that instance I just wipe the drive with diskpart feature or using the Partition Wizard wipe function - but the choice is up to you as to what you do with the drive.

Some system specs would be really helpful too mate as would what that drive make and model is
System Info - See Your System Specs

Try formatting your 500 GB drive with Ridgecrop's Fat32format.

Ridgecrop Consultants Ltd

( Click on the picture to download guiformat.exe (76KB))

Note: Your 500GB drive would have never shown as 500GB anywhere, anytime - not in Windows. Don't take us for a ride :).
For HDD manufacturers it is decimal. 1000MB = 1GB. For Windows it will be binary. 1024MB=1GB 9likewise for KBs and MBs. So for a 500GB drive you can expect it to be shown as around 465 GB.

Please give details of your 500GB hard drive Make/Model.

Did you buy it?

or did you pull it from an OEM machine? (OEMs can hide space in the HDD which the OS cannot see and will not touch as will most partitioning software..)

Go with Jumanji mate as I am not really understanding what you want to do. Good luck.