The
L4400 should be OK, Eldon. I bought an
L4300 in Dec. to do precisely what you're speaking of. It's an older version of the
L4400 which uses the same engine but an older transmission.
Though I haven't tried it at plowing yet, I don't forsee any trouble. It's got plenty of power and should handle a 2 bottom 14 inch plow with ease. If it were 1200lbs. heavier, I'd be willing to bet it could handle 3x14's.
I've pulled the same 2 bottom plow behind a 32hp, 3500# 2WD Ford 2000 and got along very well with only occasional problems from losing traction in wet spots. With 4WD and filled rears, the L4300s traction is phenomenal; it should be a big step up from the Ford 2000....well, I hope so, anyway.
There's a section called "Implement Limitations" in the
L4300's manual. In that section there's a table which lists implements and gives max recommended size for each. For the "Bottom Plow" it gives "14 in. x2". For the Disk harrow it gives a max. harrowing width of 78 inches and a max. weight of 880 lbs.
For us hobby farmers with 10-20 acres to work, this should be enough. I don't know anything about the JD990, but if weight and power are comparable it should do as well.
FWIW
Bob