ls6 engines but no cars

[69L72RS]

Dennis,
If you have the VIN from the front pad or by the oil filter boss, a good starting point would be the DMV to see if the cars are on file. Be warned that there may be some legal hurdles to get past. Some states have privacy acts in place that won't allow certain title info to be given out to the general public. Insurance and law enforcment personnel do have access to the info and might be able to help you find out if the cars are still around or stolen and parted out.
Hope that this helps.
Eric