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Simplicity 728


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Just brought home a Simplicity model 728 from a barn down the road. It has a mower deck and doesn't appear to be in terrible shape. My sons pull garden tractors in a club nearby and I want to add this to our trailer.

Tractor model 728 "Broadmoor", Ser. no. 765 003592 located on sticker behind seat. Engine is a Briggs vertical shaft Model 191700. The mower deck has mfg. no. 990422 and ser. no. 27286.

What year is this tractor?
Was/is a "good" model?
Where find owners' manual?
Where find parts manual?
I will appreciate any help/wisdom/advise that anyone is willing to share. To date, we have a couple of Bolens G12 in the 800 lb. class, and a Gravely 8123 in the 1,000 lb. class. I thought this Simplicity might work well in the 600 lb. class.

Thanks in advance,

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I looked high and low but couldn't find a Manufacturer number, the sticker behind the seat only shows serial number. The engine shows as a late 1971 model.

Anyway, on to more specific questions:

Can this frame handle a larger Briggs engine, like a newer Briggs 10 HP?

Same question about the drive train?

Can the gear ratio be changed in the transmission?

Is there a way to "lock up" the differential?

What about the rear tires; is there way to mount 12 inch rims on these wheel assemblies?

What is this thing worth if I put it in sound mechanical order and sell it?

What is it worth if I restore it to showroom and look for a collector?


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The serial number for your tractor is not very helpful in trying to determine what year it is, nor for finding parts. What you'll find much more useful is the Manufacturer Number, which I suspect is 990577, since that's the only 728 listed in the X-reference table.

Since this model does not cross-reference to an AC, I can't help you determine the year of manufacture. I'd guess that it's probably about a 1970 or 1971 -- but this IS ONLY a guess, since the 1969 (in the Catalog) was a 727 (7HP)....

There should be a serial number for the engine that may help -- if it is the original engine. This number should follow the model number that you've listed above. However, it could still be "off" several months from the date the tractor was manufactured.

It's a great little tractor for its original purpose -- but I can't speak to its potential as a puller...

You can get most owners, parts and service manuals through the Simplicity dealer network, or direct from Simplicity's publications department. There's a link on the Links page that will get you to that info on the publications department. They're very courteous and fast (usually a 3-5 day delivery time).... Should they not be able to provide them, let us know, and we can probably come up with alternatives....

Hope this helps -- others please expand/correct as needed....

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