Combines 4row narrow on R42IJ

I have an R40 with a 4 row (36 in rows) and on steep side hills the back end will slide down the hill and the spreader will just leave a trail of ears on the ground. I have to keep the spreader on the downside away from standing corn. Not to much problem with the other side. With 30 in rows I would think you would have problems with a 4 row head. Bother-in-law (he has a 9400 JD) went to a 5 row head with a eight row planter. Said it worked OK. He plants straighter than I do though.

My father in law tried to do a neibors corn one year that was 4 row wide and he has 4 row narrow. You could only do 2 row or the snoots would get to far out of the rows.

Don't know about the R42, but I run an F2 with 28 inch tires behind an 830 JD planter. Extended the markers two inches. Tires run within 4-6 inches of the row, need to drive the planter straight. Pull out the tape measure to see how your combine fits, mark the row location on the tire to see if it fits.