When jumper cables go directly on positive post of the starter, and starter to bell housing bolt for negative, exact same thing happens. No better, no worse.
No matter if source from rabbit's own battery or coming from a running 1 ton diesel with 2 batteries.
Could it be something with the motor that makes it harder to turn over?
I can turn it by hand, but it does have on spot that seams to have a lot of compression, making it tougher to turn.
So to summarize,
1. No voltage drop anywhere.
2. Can put jumper cable on any way you can imagine, multiple times, expecting different results, but always the same out come.
3. Rebuilt starter w/bushing (did this with previous starter that was 4 months old), new alt., good battery, new battery cables.
4. Bell housing tight against block. Starter tight against bell housing.
5. Motor turns very little, but does turn. Better on first try, less so the more I hit the key.
6. Flywheel has a little wear on outside corner of teeth, maybe 1/16'' rounded, some spots a little less.
7. Don't know what to do next, maybe get out a sledge hammer just to make me feel better.