Need help to find.

[deadboy]

Don't rush too quickly so you wont get crazy while searching. Take your time and search everyday 1-2 hours for them.
Monroe is pretty much the hardest. It took me one week (like I said, everyday a little bit).

You can also try the Premium-Helper while looking for parts for Unique Cars, it will make your screen flash white (whole screen gets white and fades out after 1-2 seconds), you have to be around 20 meters near the part.
It's really helpful, I found the last parts for Mamba and Countash that way. It's not even expensive 2€ for 7 days of premium (which is more than enough to find the parts). Protip if you don't got a paypal account: Do one and charge it with a paysafe card.