I ordered the black cap and white diamond from Midway USA and it worked perfectly! I cut around the edge where the cap joins the stock with a razor and then popped the old white diamond out with a small screw driver. Then, I could access the screw holding the cap on and removed it. I installed the new cap and it fit perfect! I placed a small dab of gorilla glue under the new diamond and pushed it in. I looks perfect!!!
I also order a new black plastic butt plate and white spacer for the buttstock, but my gun is an early 80's version and the new buttplate and spacer are larger than the one's on my gun. The butt plate was about 1/4 in. longer and the white spacer is larger also, and is bigger than the new buttplate (about 1/16 in all the way around).
Does anyone know where I can get a new black plastic butt plate for an early 80's gun? Mine is in pretty good shape, but was covered in the clear finish from the factory and it has chipped a little. I would like to replace it as well.