what kind of motor mount

i have a 73 duster 360 was 318, want to change motor mounts from soild to rubber, went to parts store they gave me the wrong ones, now cant find any none of the books has mine in them. mine is kinda square where it bolts to motor and has a smaller round part where bolt goes into k frame, the one they gave me is longer where it bolts to motor and bigger around where the bolt goes through and will not fit its to big anybody have this problem before and know where i can get right ones, maybe part # will try to send pic of mine? thanks