John,
counting the spacers to date a 72 to 86 100 series knife is a fairly new option. Very little information was available so many assumptions had to be made. Here it is in a nutshell.
1972 should be the only year the stamp is read with the point towards the ground. aka inverted or upside down. The guard has 2 micarta spacers and 2 aluminum, pommel has 2 micarta and one alum.
In 1973 the stamp will be read with the point towards the cieling. The guard has 2 micarta spacers and 2 aluminum, pommel has 2 micarta and one alum. This configuration was used until about 1980.
In about 1981 the knives will only have 1 micarta spacer and 2 alum. in the guard and the pommel will still have 2 micarta and 1 alum.
Later in the same year the knives were changed so that now the pommel only has 1 micarta spacer. This takes us to 1986.
I hope this helps,
