1951, Ferguson Model To 20 Or 30

My brother-in-law says my dad's Ferguson is a Model 20 but my internet acquantence thinks it's a 30. My brother-in-law says it's a Contentinal engine therefore a 1948 20? It has the oil filter on the side of the motor instead of in the oil pan which makes by internet friend think it's a 30. My dad's insurance policy has it as a 30, he died last May. We're having a estate farm sale soon & would like to know for sure. I respect my brother-in-law a lot, I suspect he's correct. But if it is truly a 30 it's supposely has more value. Sooo, anybody? Photo was taken a month or 2 ago. He bought it on a farm auction I think. Model No.under the steering wheel is TO#60936. Engine # is Z129E301089. My brother took the serial # down, suppose he misread the the 3rd number a '0' as a '9'? The front tire size are 6.00x16 if I read it right. 12.4x28 on the rear. Sale Nov. 2nd. Submitted by Dennis Stuhr, from AZ