This is a transmission rebuild kit for the gas or diesel Mazda B2000 5 speed truck manual transmission used for years 1979-84 BK137WS This transmission uses a 15mm wide single ball front countershaft bearing and has a smooth case with no ribs. The 1st-4th synchro rings have 30 teeth. This kit comes with all the main roller bearings, counter roller bearings, input pocket needle bearing, seals, gaskets, and complete set of high quality synchro rings. Note: The pocket bearing K20/24/25 is no longer available it has been discontinued.