Joe,

I took dimensions off of the bracket on the 59. The mounting holes on the block looks the same as the 55 sitting next to it.
There are 3- 5/16" tapped holes in the block.The first one is 3/4 from the inside of the front bracket ear. The next is 1 5/16 from the first hole and the 3rd is 3 3/4 from the first hole. The bracket is 1/4 thick. From the gen./alt mounting hole to the inside of the bracket is 5/8 high. Add the 1/4 thickness and it is 7/8 to the bottom surface that bolts to the block. I tried to be as accurate as possible, but the gen. is still on the engine and the engine is sitting on a cradle on the floor so it was hard to measure. These dimensions should be very close though. The bolt spacing should be right on because the 55 has no bracket on it. I measured the holes in the block. I would think 3/8 clearance holes would be ok for the block mounting holes or even oversize would allow some adjustment. If you need more info or better descriptions let me know.

Roy