Good morning lachlane,
Thank you for your quick response.
If the engine is a Briggs and Stratton, you can use this link below to get specific information on your motor. It requires a 6-digit Model number and the first 4-digits of the Type number.

http://www.briggsandstratton.com/us/en/support/manuals/engine

Some of the older Briggs and Stratton engines only had a 5-digit number and, in this situation, you just add a "0" (Zero) in front of the model number to make it up to 6 characters.

Once you do a search, you may get several results for the engine Model & Type input. If this is the case, just look for the number that matches your machine. For example, on the B&S above, I would look for 280777-0675-E1, and then you have your manual choices of Parts Lists and Owners/Operators Manual.

Here's an ODK thread I found that you may find interesting for a Chassis number:-

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=33632

It seems the easiest way to help ID a Greenfield, is to prove photos. :-)

Environmentally friendly recycling at it's best