I've replaced some of the knobs on my graders...with Dorman 76933 gear shift knobs...that I found at my local auto parts house...for $10.63 ea...I notice that these knobs are also on e-bay from @ $8-$13...These knobs are the same size as the original CAT knobs...Easy fix/change out...
Just a helpful hint...
Respy, CarlsCat...