Hi Chuck,
Before you spend a lot of time hunting through a junkyard trying to find a pulley....you might want to consider an alternative to ruining a new pump and not solving any of your trucks cooling issues.
The option I mention is using the "adaptor plate" and the early 216-235 pump which comes with the correct 4-1/4" OD pulley. I've tried making my own short pump and even fabricated a pulley. The problem is that even though you can gain some fan/radiator clearance you do nothing to raise the pump up so it centers on the radiator. In addition, with the pump mounted low, there were issues with fan to harmonic balancer clearance and you are restricted to using a small diameter fan. All of this led to an engine running on the hot side.
I took some good advice and purchased the "adaptor plate" which repositions the water pump higher on the block and centered on the radiator. The "early" waterpump is available at most local parts houses in both 3/8" and 5/8" belt widths. In addition I could run a 15" 6 blade fan and had NO issues with fan to balancer clearance. The cost of the adaptor plate is very reasonable and installation isn't that complicated. A couple holes have to be drilled/tapped in the block and this was easily accomplished with a battery powered drill. You DO NOT drill into the water jacket and the installation instructions will guide you through the process. I have pictures of the completed install and the instruction sheets in my webshots albums. One highlights the drilling process.
I purchased my plate from Pre68Dave on this forum and there are others offered on Ebay. After struggling with the modification of a stock pump, then purchasing the overpriced "short-shaft" pump which was a complete waste of money, I went with the adaptor plate and highly recommend it as the final solution to clearance and cooling issues when installing a late model 235 in an early AD truck.
Dave
