Small Engines (Lawn Mowers, etc.): Where to find parts, briggs and stratton, hp briggs

Question
Hello.
I have a Brentwood front tine rototiller. It has a 5 hp Briggs and Stratton motor on the chassis.  There are no model or serial numbers on the unit.  There is an area at the back of the chassis where a sticker would have been, but it appears it disappeared a long time ago. This is an old unit. It was my fathers 25 or so years ago, and it was used then.  I just dug it out of my mothers shed and got the motor running like a dream.
What my problem is, the axle oil seals on the tine drive shaft are old, cracked, rotten and leaking.  I pulled the left one and they need replacing.
I can't find any information on Brentwood brand rototillers to find a place to get parts.
The seal measures out as: 1" ID , 1 1/2" OD, 5/16 width.  
Any information about this make of tiller such as where to find parts, a manual, an exploded parts diagram etc would be a great help and appreciated.
Thank You
Sean

Answer
Maybe Gilson Bros.  They were bought by OMC and they sold it to Toro.  So Toro is the answer maybe.  Anything this old will be on micro fiche.  You would have to contact their parts department and get someone to do the research.  There is not a list of names they produced for.

The other would be MTD.  Again same thing.  As far as the oil seal goes measure the shaft size, I do not think they used special seals to build a tiller.  They would have been way to expensive.  Purchase the seal to fit the shaft and it should be standard.  Should be available on line search oil seals and you will get a pages of options.