On the WD and WD45:::
Final drive pinion: 15 tooth, final drive "bull gear": 82 tooth.
Differential ring gear on both tractors, (although different part numbers) are both 43 tooth.
WD45 Differential pinion tooth count??
Early WD differential pinion tooth count: 12.
Wish I could offer a little better help that this, but I believe the the extra set of worn out WD45 gears that I hung onto for 28 years went in my last scrap iron clean-up..
I will double check and see if those gears got thrown. I"ll get back; with a tooth count if I find them... I have a reproduction parts book that lists the tooth counts for all the early WD transmission gears,<> but it is my understanding that you have the complete information on the early transmission, If not, just yell...
Best of luck on your project, BDT