This came with various engines including CH18S-62599 and CH22S-66549. The shaft on this is 1-1/8" x 2-3/4". Any engine you buy may requre parts from your original engine or modifications. If you buy one with a longer shaft, you can cut it as needed or add a sleeve at the end to hold the electric clutch on. If you use either the CH620-0017 or CH740-0124 engines, there may be minor differences like wiring, air breather, throttle and choke controls. Parts should be interchangeable as needed. The shaft is 4" long but can be cut down as needed.