Small Engines (Lawn Mowers, etc.): MTD Yard Machine Tiller; Briggs 5.5 hp OHV, tool lending library, google search

Question
Engine oil and gear oil;  Fill-ports (& caps) have no ID, no dipstick.  This poor machine is in my community "tool lending library".  As usual, it's suffered, and had little or no mntnc.  I want to change oil ... especially since I believe I've added gear oil to the wrong port today :(  Ran 30 seconds and put out huge cloud of white smoke.  I cut the engine right away.   PLEASE advise on correct ports;  How to change the engine oil;  I figure using 30W engine oil, and 90W gear oil (?)  IS a dipstick missing?    Mod. no.  is 21A-332B729 736-325;  Ser. no. 1K044K50368
MUCH THANKS!

Answer
Call MTD at 1-800-800-7310  I have tried to get you a manual from their site with the numbers you provided.  Here is the address to get a manual from mtd.
 http://manuals.mtdproducts.com/mtd/Public.do

a quick google search of the number you provided tells me you are not alone in your question.

Hope this helps...