Manual Transmission Countershaft Clearance Inspection . Transmission Reassembly 13-3 13-2 Outline of Model changes ~ Countershaft clearance inspectian has been changed. - Reverse idler gear shah boll torque has been changed. o The F18A3 engine has been added. The transmission used with this engine is the N254 transmission (the same type as used wilh the F2021 engine).