Jeff,
Maybe repost this question in the big bolts section. I don't have info on the Clark, but it should have the brake on it.
As for the NV4500 certain versions have it others don't. I believe the early chevy 2wd version has a brake, but it doesn't match up to your bellhousing. The dodge version will bolt up with an adapter plate. You might have to get a hybrid NV4500, dodge input shaft, and chevy tailshaft. One more Monkey Wrench to throw in the works... The speedometer is easier to hook upwith the dodge version. You might check to see if any of the chevy units with the break even have a speedo gear. The chevys used a velocity sensor, and I think the sensor lived in the rear axle.
