GRADE 51, MODEL 6, 17-JEWELS,ADJUSTED,SAFETY PINION. PRIVATE LABEL.DIAL AND MOVEMENT MARKED C.A.WILLIAMS TERRE HAUTE,IND. MY RESEARCH SHOWS 1,970 TOTAL OF GRADE 51 17 JEWELS MADE. MOST WERE 15 JEWELS AND A FEW 21 JEWELS. WAS RRG AT THE TIME. I CAN'T FIND GRADE 51 IN THE"FAT BOOK" ANY COMMENTS WELCOME.