D5 is a particular series of Caterpillar bulldozers. D3, D5, D8...etc. larger and smaller.
D5 is a nice mid-sized unit capable of moving decent quantities of dirt, while still being nimble enough to make small features.
Most golf course constructors rent the equipment because shipping it all over the place from job to job is not always cost effective.
Sounds like Chris is handling the procurement of the 'dozer Doak et al will be using to shape the course.
As an aside, I imagine they are going to be using something a wee bit more modern than the unit Kalen displayed an image of.
Probably more like this...