Serial number on 2020

I'm shopping for a tractor for a neighbor. I found this 2020 but don't know much about them. I'm trying to make sense of the serial number. Here's what I saw on the tag:

SNI 5H3C028221T

When I look at the s/n charts I just see numbers, not letters. Is the s/n just the numbers between the C and the T? 028221? If so, do we call this a 1966? What do all the other letters mean?

thanks!

The 2020 has 54 hp. The "HU" would normally indicate a taller tractor (36" rears), but the tractor in the photo appears to have the shorter 28" or 30" rears. The "LU" would normally have 24" rears, and the "RU" would have 28" rears. The transmission has eight forward speeds and four reverse. It looks as if the paint is original, is it? How many hours on the hour-meter? What is the dealer's asking price?

T - Indicates "tractor"
5 - Indicates series, "2020"
H - Indicates model, "HU"
3 - Indicates diesel engine
C - Indicates collar shift transmission

You are correct that the "028221" is the serial # from which you can determine that the date of manufacture was 1966.

T - Indicates the tractor was built in Dubuque, IA

My neighbor just wants something to mow his 10 acres and he's sure he wants live PTO. I think this unit is probably overkill, but that's usually better than not getting enough tractor.