[prairieschooner]

My model 3425J Alternator was been rebuilt at a cost of $425.00 and required a new Stator, Rotor and Regulator (the independent lost my Regulator and other internal parts). I was lucky to find a shop at the Port of Long Beach that had parts, not sure that another shop could do this type of repair for much less.
The 1st shop that I went to was not qualified and lost parts. This is why I recommend that you tread lightly.

The Gear Driven Alternator is mounted to the rear of the engine high and on centerline. The Seal that is on the Adapter Flange was the weak link and Detroit changed the type to Viton. Anyway if anyone sees debris at the lower portion of the alternator then the seal is most likely in poor condition and should be renewed. The debris is most likely showing an oil leak from a worn out seal with dirt collecting near the base. This could save allot of expense if caught in time. A new Gasket is less than $6.00 and the proper seal is less than $20.00 from DD (the seal is different than what is normally supplied by a Bearing House, Viton rather than Buna-N.

Replacement Seal Detroit Diesel #23508977, and get a Flange Gasket #23509123 on our 6V92.