I don't think there's any way to tell. The numbers on the radiator support are the build numbers, and they would normally match the numbers on the fender tag. If both are missing, I can't think of any way to tell.

Are you planning on registering this car?

 

that would be difficult unless you get lucky and find some other info like the old registration or maybe old dealer info that would match.

 

if the cars still got the orig. int. in it look for the build sheet under the back seat, or stuck to the back side of the glove box liner. thatll give you what you need. since it ws a theft vehicle, have the local p.d. check with a place in michigan, I beleive. theres an archive place for this purpose. all vehicles built in the us since like the late 50`s send all the daily build info to this place and they store it all on microfisch, if your a cop or ins. under writer, you can get the info. they should know the name of it and where its at. small chance , but if the orig. motors still in the car, the vins stamped on the pan rail. at least youll find out which plant it was built at. If you get the vin off the rad support, you can also contact galen gavier in wis. for a fee , he has build records, he may be able to help you. good luck.