OEM 45cc cylinder block kit/rotating group Deere AT351935. 
 
Fits many 300 series skid steer loaders and compact track loaders:
325
328
318D
319D
320D
323D
326D
328D
318E (S/N G253889-) (S/N J249323-)
319E (S/N G254929-) (S/N J249321-)
320E (S/N G254913-) (S/N J249291-)
323E (S/N G254917-) (S/N J249322-)
326E (S/N G254998-) (S/N J247388-)
328E (S/N E236673-)
329E (S/N E236704-)
332E (S/N E236670-)
333E (S/N E236690-)
 
....and many others.
 
Please contact us if you are not sure it fits your machine.