Denso starters use a very good, long lasting brush material. It is common for these brushes to last 200,000 miles without a problem, although sometimes in trucks used off road, water intrusion can cause early wear. Common symptoms are slow cranking but check your batteries and cables first. Brushes should be replaced when there is less than 2mm clearance between pigtail and brush holder, in other words if the brush can only move 2mm more toward the commutator when wearing.
Crossover part # ALLISCHALM 272028, CASE A47239, DAIHATSU 28140-77090-000, DENSO 028510-0500, 028510-0501, ISUZU 5-81118-013-0, JOHNDEERE AR74294, CH12502, KUBOTA 15451-63381
See Exploded View of this part in the starter HERE