Some of the original specs were 69531, 69554, 69545, CV730-0032. The crankshaft on these engines is 1-1/8" x 3-5/32". You can use a longer shaft, but you may have to cut it off or add a spacer at the bottom to keep the pulleys from moving. This engine also utilizes an air cleaner that mounts horizontally so the muffler sits directly under it. If you buy an engine that is not this way, you will have to change it and all the throttle linkage as well. If you use the CV740S-0029 There may be minor differences like wiring, air breather, throttle and choke controls. However, parts should be interchangeable as needed. You will have to use the muffler of the old engine.