Thanks for all the input so far guys. I have been searching around and most of the 61Ms I found had the radiator in the front with a small opening/grille. Then I found this one. A 1971 Lotus 61M. Apparently they made 250 different versions of them.
As you can see it has the raditor mounted on the left side. Larry, as for the rear being different you are correct. I think the one I have is a mold for a Lola T-340. The one above pictured appears not to have any but the others I have seen have the same back as you mention. Now, just to figure out the frame. The Lotus have the stamped sheet metal dash area. Mine doesn't. It also has the frame stepped in on the outer rails also and looks as though that is where the rear of the upper A arms attach. Thanks again for the help.
Graham.