Caterpillar 158-4765 Bottom Roller Assembly The bottom roller with part number 158-4765 is an aftermarket track roller for multiple Caterpillar mini excavators. Details are as follows: I. Core Compatible Models Fits the following Caterpillar and Mitsubishi mini excavators: Caterpillar: 304, 304.5, 305.5, 304CR, 305CR, 306 Mitsubishi: MM 45 II. Alternate Part Numbers Replaces Caterpillar original part numbers: 158-4765, 340-8957 Caterpillar Dealer Part Numbers: 158-4765, 340-8957, 333-5606 III. Installation Quantity and Instructions Quantity per Machine: Caterpillar 304CR: 8 rollers per machine Caterpillar 305CR and 304.5: 10 rollers per machine Mounting Hardware Note: These replacement rollers do not include the 10mm bolt required for installation, which needs to be prepared separately. IV. Fit Guarantee There are no known alternate part listings. This track roller is guaranteed to fit the listed models precisely.