a few differences---the slave cylinder is external, so servicing is much easier; you do not have to replace the pressure plate; and even with the recent $300 price drop for hvda, Bill is still more than $300 cheaper. further, Bill can provide a light weight, balanced drive shaft, and he likely can assist in locating a good, compatible transmission (which he did for me). i was able to buy the conversion kit with transmission for less than the original cost of the hvda bellhousing alone.