I noticed some weird discrepancies in the JD 5020 Tests section between
NTTL 947 & 1025. The max pull is much higher for the earlier engine despite
having lower HP. I looked through the test and realized the 947 tests were
performed with much higher ballast weight. I'm curious if you know anything
about why Nebraska would do that?
In that era, the manufacturer was able to pick the ballast for the drawbar
tests (in the modern test, no ballast is allowed). I would guess that Deere was
going for a higher drawbar power rating, which they achieved by running
faster. Drawbar power was often used in the sales literature but almost no
one used maximum pull (except crawlers).