Hello there. I have been collecting and dealing with Transformers since they came out in 1984. This guide will help you identify an original G1 Transformer from a Re-issue G1 Transfromer. 

It is very easy to distinguish the two as long as you know what you are looking for.  Sometimes it is hard to tell the difference between the two because the molds that were used are identical.  However, there is a very easy method that you can employ. If you look for the manufacturer's stamp, it will have the date of manufacturing and it will also have Takara and/or Hasbro along side it.  The stamp may even have Japanese symbols.  Generally, all the original G1 Transformers were made in Japan and they are marked accordingly. The newer G1 Re-issue Transformers are made in China and stamped accordingly. The dates for the original G1 Transformer line ranged from as early as 1974 to 1986.  Compared to the much newer dates on the Re-issue Transformer lines. 

I hope that this guide helps you. Let me know if you have any comments or questions.  Thanks, ltinc.