Ive never heard of tractor model dates referenced with tractors when the model designation stays the same. Clearly, a
BX2660 is older than a
BX2670. Does it matter otherwise? If used, we look at hours.
Question is, how will I know if a new tractor is a leftover from last year, or a new one just out of the crate? I want the newest updates... or does Kubota not do Build 1, Build2, Build 3, etc. for mid production changes like auto makers.
I don't know anything about other than Kubota brands since all I've bought is/are Kubotas. Since you've asked this on the Kubota forum I'll give/tell what I know and why I know? it.

I was talking to Barlows main mechanic one day about a question concerning the F model Kubota and any history with a specific issue that it has. He said he did not know of any and that Kubota would have fixed the issue when they discovered it which to me seems like mid run. Running machines and 3 weeks later on a Wednesday engineers have discovered a problem that is cropping up then the assembly line will be provided with the "new" parts/fix and the line keeps running. Question is whether they will recall all previous machines, I doubt it unless they determine there will be more expensive warranty work ahead. My conclusion is that the first
BX2660 produced will NOT be exactly like the one produced 1, 2 or 3 years later but they will basically be the same.
The BX??50 series has some issues, the abrupt stop in reverse being the main one, and so the 50 series was a short running series and never heard of any of them being changed mid run, "believe" Kubota discovered the problem as the complaints started building up and (Reimbursed me $500 because of it) fixed the issue(s) and started the BX??60 series which has ran for several years till this year became the BX??70 series.
OK, that's my input from a Kubota owner, not just a tractor of some brand owner and they ain't all the same which is why they are different prices.
If I was buying a 2 year old lower hours tractor I'd want to know the year of production and year of sell, if available. If I was buying a thousand hour machine that was/is several years old I'd not be as concerned with manuf year, myself, within a couple of years.
Actually I did buy a
B7100 Kubota a few months ago with 1000 hours and don't know for sure what year it is but did research the years of production on the model after I bought it but bought for cheap enough that year doesn't matter. Steve Barlow is to look at it today for possible trade and he didn't ask me what year it is.
The
BX24 was in the BX??50 series and
BX25 replaced it thru 2013 which has now changed to
BX25D with a few changes but same basic machine.
I got rid of my
BX2350 pretty quick and went to a
BX2660. Almost like trading brands in the difference between them. I had owned some BXs and Bs before I got the
BX2350 so I knew it was "wrong" for a Kubota.