Welcome to the site. Its odd that you cannot find any casting numbers. Deere normally has many of them in different areas. LP tractors were not popular in my area and I have never seen one. Sorry I cannot help!
Thanks very much. I've been asking other green folks and they didn't know. This tractor is located a long ways out in the countryside from where I live, but I'm hoping to go back soon to get it ready to haul home. The engine is stuck, so I've got my Kroil inventory increased just for this purpose. Even ordered some of that product called, "Knock'er Loose" to try on the stuck pistons, in case the Kroil doesn't get em to budge. Thanks again for your help.Here is what I found. Check this out.
http://www.tractordata.com/farm-tractors/000/0/3/37-john-deere-70-photos.html
Be sure to look at the last photo.
And, WELCOME TO THE FUN!