identify frame?

[JQE80]

I bought a frame about 5 years ago when my 79 got wrecked so I coule swap the cab over and rebuild the truck but I can't remember what year the frame is from. Can anyone tell me how to tell the difference in the frames? Also I think I going to replace my leafs, anybody know a good place to find some? I tried to search for about an hour with no luck. I am hoping to finally get this project started up again after the long delay.

Thanks
Jarrid