Wiring diagrams for a Dayton winch #3VJ74 seem to be rare online and not even Google Images could produce such a diagram. The best diagram available appears to be the one on fixya.com, which I've reproduced below:
This aside, there are lots of Dayton items for sale on eBay, so perhaps one of the sellers could be persuaded to reproduce a copy of the manual for you.
You could of course contact Dayton themselves, but I have been unable to find their customer service number online. If you ask at your nearest Dayton stockist, or consult the packaging of a Dayton item at the store, this might help you further.
Finally, you could try gemplers.com/docs/manual, which offers PDFs of some Dayton products, you may be able to find a diagram for your winch there, or you could ask around in a forum like homeappliance.manualsonline.com.
I hope this is of help you, and good luck with the winch!