Cab Entry Battery Box, Aluminum Diamond Plate, 31 Inch Step Box for Peterbilt 378, 379,389, Step Battery Box. Cab Entry Battery Box, Aluminum Diamond Plate, Step battery box Dimensions: 19″(H) x 30″(D) x 31(W) Quality Parts with Aluminium, Durable and reliable during various weather conditions Built with durable, corrosion-resistant. Thick smooth aluminum body and. Diamond tread door with reinforced corners. For Peterbilt 378, 379,389. As our valued customer, we will do our best to make sure the product you receive arrives to you on time and as expected.