[1966 Riviera driveshaft]

There can be differences between different trims of this model. Better get the part that matches your exact trim. For the trim, look at either the owners manual or lookup by vin or even do a licence plate lookup here - https://www.autodetective.com/license-plate-lookup/

[Title Issue Resolved]

Be careful though, even though you are sure of your car history and know its title is clean, it might not always be the case. Maybe you should get its history checked yourself too. Just google vin check online and take any of the tools available to check it. Here's a couple of useful things for you:
- how to read the vin report https://cars.usnews.com/cars-trucks/what-do-vehicle-history-reports-say 
- a sample tool I found online for free vin check https://www.autodetective.com/
- what the whole vin thing is about and how it works https://wiki2.org/en/Vehicle_history_report

[Fraudulent VIN question]

You can also check the vehicle history report by yourself, and if there will occur any problem or weird thing noticed, then you you should request your issues to DMW. I have mentioned one the free tools, but you can check it other way as well. Good luck. 

[Looking for VIN location for a 1955 Ford F250 Pickup]

On my 55 F100 I have not noticed a VIN on the radiator member. There is one on the top of the righthand frame rail 4.5 feet back from the front end of the frame.