What model is this JD plow?

[Red Raider]

I believe this was probably bought in the 40s or 50s, but that's a guess. Would like to know model so I can buy a coulter for the front. Second, any ideas on where to get a coulter? Thanks.

 

[ctlguy]

Looks like maybe a "ab" or "ag" plow with HS bottoms. Can't tell for sure, look for a cast # on any of the cast items, frame especially as the bottoms are a different piece of equipment and can probably figure it out. If buying the complete coulter assy go to a JD dealer and look at pics for the newer 4200 plow, or a case/ih dealer and look at pics for a 145 plow.