I bought a GT19 several months ago with a daylight block in the KT19-Series II.
I've measure my engine for several engines, including Honda V-twin, a B&S twin IC engine, A Kohler CH18 V twin, and a Ruggerini 2 cylinder diesel (Ariens put them in the GT18D, but stretched the frame 4").
The Honda's crankshaft centerline is about 1" lower than the KT19 engine... the bolt spacing side to side is the same but different front to rear. If you use a spacer to bring it up even--necessary if you use the fiberglass discs in the flywheel coupling, then the hood hits the top of the cylinders... A person might could raise the front grill 3/4 inch by putting a steel spacer under it, and move the dashboard up by putting some brackets under it. Haven't got that far so I don't know for sure if that would work.
The B&S has the same shaft centerline, but the mounting holes don't match front to rear.
The Ruggerini has a crankshaft centerline about 3/4" higher than the KT19, -- it will fit in the engine compartment, but would require either cutting the hood for the exhaust, or some fancy work with exhaust tubing. The oil filter is also blocked by the frame.
The Kohler Command 18 has the same "footprint" for the mounting holes and the same crankshaft center height, and, near as I can tell, the same position of the flywheel, etc. to the KT19 but I haven't measured for the clearance from the top of the engine to the hood.
I just bought a CH18, so I'll be checking this soon as I want to get my GT 18.5 running ASAP.
Also, bear in mind that the manual Ross steering gear if VERY close to the drive shaft so you'd have to be creative if you decide to use U-joints..
--AND-- The engine sits offset to the driver's right (sitting in the seat) about 1" so that may throw a wrench in the works.
Edited by Utah Smitty, May 01, 2015 - 11:28 PM.