Grendel, are you talking about the high mount AC parts? If you have a 4bt, those parts will mount to it. They never came on a 4bt but were on tons of 6bt's in trucks and buses. One area you have to be aware of is the engine mounts. The bottom bolts in that AC mount occupy the holes often used for the engine mounts on a 4bt. There can be other minor issues depending on what vehicle you plan to put it in. Biggest issue is often the cost. Tennessee Diesel Conversions sells the complete setup excluding the bolts for $1425. See photo below. Might seem expensive, which it is, but those parts are all Cummins except the compressor and alternator. If you could get the parts off an engine in a salvage yard you may save quite a bit. There are also AC brackets that put the compressor on the driver's side of the vehicle. Those were often found on Case backhoes. The AC compressor on those runs off a separate V belt instead of the 8 groove. Not a cheap setup either but less than the other one.