How many teeth drive my Speedo gear?
 

I am trying to figure out my gear ratios before and after swapping a manual transmission in place of an automatic transmission. The question before and after the swap I need answered is how many teeth drive my speedo gear? I have an ‘84 Blazer with a 700r4 transmission and new process 208 transfer case that I am replacing with a SM465 transmission and new process 205 transfer case. I would imagine that the answer is different for the two different set ups but I clearly have no idea where the teeth are in order to count them. Any help?