This Rotax 503 F/C twin cylinder engine is in great shape and is for oil injection (has the square key way in the mag end of the crankshaft.  This listing is for the engine as pictured and there is no core required for this engine.  S/H on the engine is $65 in the Cont. US via UPS Ground, $195 for USPS Priority Mail International to Canada, or $275 for USPS Priority Mail International to the UK.  Local pickup is welcome as well. Also we can ship this engine to other countries internationally but please email me before you buy for an accurate shipping quote.  Let me know if you have any questions. Thanks, -Paul (616) 693-2538