Thanks again for your help. I just bought the new engine after speaking with Briggs tech support. Officially, the replacement engine is the exact same model, but unofficially any of the models should work assuming the same drive shaft length and width. The exhaust system is the same for all of these Briggs models. I got a great deal on that 25hp engine and will be installing it over the next couple of weeks, hopefully before it's time to mow again.

I'll update this thread when I'm done, for other's future reference.

I have the same problem with my L120 (only 200 hours), the engine is shot. Local mechanic is saying it will cost $1500.00 to fix, that seems really high to me. If you don't mind, what did you pay for the engine replacement and how hard is it to swap out. My knowledge of small engines is minimal but I do work on cars and motorcycles. Is it hard? Any help would be great. Thanks

Hi,
Best price and engine I found was the 44L777-0115 for $574.95 at:
Briggs & Stratton 44L777-0115 23 H.P. (http://www.smallenginesuppliers.com/shop/html/pages/products/briggs_vertical_shaft_engines4379.html)
Peace,
Clarke