Info about the Briggs 49M977-1036G5 engine.
I installed this same engine on my Scag ZTR last March, nice engine. but with a GT, you need to know the following:
This engine is taller due to the Cyclonic Air Filtration System, in two ways, the blower housing is about 2" taller and the air filter housing is about 3-4" above the blower housing, so make sure there is enough room under the tractor hood to accommodate the added height. You will also need a Briggs muffler. Electrically, there are the same inputs/outputs as the Kohler, just different connector plugs, you will need to identify them and connect accordingly. You will need a separate engine start solenoid. There is also the possibility that the engine mounting holes in the tractor may not be the same holes for mounting the Briggs engine. Some tractor manufacturers drill mount holes for different engine options and your tractor may already have the different hole patterns.
There is a trend with newer engines where the amount of throw for both the throttle and choke is less than older engines. On my Scag ZTR, I installed a stop plate on the throttle lever on the idle side, and I adjusted the choke so I get full choke at about 2/3rds of the lever movement and full open at the other end of the lever travel.
If your Kohler has a 1 1/8" X 4 5/16" crankshaft, then the drive belt pulley and the clutch should mount directly onto the Briggs engine with no V belt or clutch anti-rotation stop problems.
You do need to know exactly what the Kohler crankshaft dimensions are before you order and new engine.
Mad Mackie in snow bound CT:laughing::biggrin::smile: