General Motors offers both the Vortec 454 and 6.5 liter diesel for their Class C type chassis, but the GM diesel is much less popular in the industry. Dodge, on the other hand, offers the 360ci in the Class C model. In all cases, weight distribution and weight capabilities will be the most important factor in your choice. Even though the chassis has weight ratings for the load, weight distribution is very critical on how the coach will handle. The rule of thumb is, if the overhang from the rear wheels to the rear bumper is excessive, you'll find the lighter the steering will feel on the road.
Some coach builders add the air bags as standard equipment.
Class C chassis are heavy-duty van chassis and when the coach manufacturer constructs an excessively long body, it results in a long overhang behind the rear axle causing the handling to suffer. If the coach manufacturer cuts and stretches the frame rails between the axles, they can distribute the weight on springs more evenly for controlled handling. In other words, if they build it wide, high and long on a standard chassis, be ready to hang on and fight the road. If you see a greater than ten foot overhang from the rear axle to the back bumper, look at the frame rail and see if the coach manufacturer added frame rail extensions. You will only see this on gas or front diesel engine models.