Have what is believed to be a 426 max wedge block, but not really sure. The casting numbers on the passenger side are 1316. On the driver side there are no numbers except for a single 6 near the rear of the block. The stamp pad has the numbers A426 and under those is a 6 10. Also on the back of the block was an R. There were no number stamped in the pan rail. Any help decoding this would be great.