frame pic to z'd today...

[boomer]

http://i117.photobucket.com/albums/o...ictures281.jpg

This is a picture of my passenger side frame rail before the tubing was in.

Can someone mark out on this picture approximately where to do the vertical cut for the zing of the frame, there is lots of pictures on the site i am aware but this is a clear pic of what i am cutting so it may be more exact for me.
It's an 87 gmc 1/2 ton.

Ive seen guys use a marker or something of that nature and draw on these pics. Not sure how but im sure someone can pull it off.

Thanks alot.