Allison 1000/2000 & Internal 1st Design 2wd or 4wd (Shallow Pan) Black Filter Fits: 2000 -Early 2006 The internal filter should be changed and the pan dropped periodically to ensure that this filter has not trapped metal filings which are a tell tale sign of an internal problem, especially when towing a hefty load. Every 60 to 70K miles is a good time to consider doing this flush. Cheap insurance is better then an expensive rebuild that could have been prevented. If you need a rebuild kit, Tech Manual spin on filter or parts for your Allison rebuild please see our store or ask us we will be glad to accommodate all of your part needs.