Photos will help a lot...particularly photos of the interior/dash, the frame, the suspension, the front of the frame where the radiator mounts, the area where the differential is mounted.
If the number on the frame were NAF975 I would say North American Fiberglass...a very fine replica. Are you sure there's not an A in there?
Others who are more familiar with the information needed to identify the manufacturer will probably be along shortly....but in the meantime, please get the digital camera out and get some photos.
Cheers, and good luck!!
Dugly
