I have a set of diamond K frame grips that are tapered down similar to cokes for double action shooting. The strange thing are that these are flat on the inside and there is a plastic spacer that covers the front strap and bottom with a pin on the bottom that holds them on. Never seen a pair like this. Can anyone tell me what they are?

I have never seen a pair, but I believe the first ever K targets were of a three piece design - maybe this is what you have.
Please post pictures!