drive shaft dimensions?

[68C15]

1971 500 # 3011762 I have decided to have my rusted-pitted drive shaft repaired by a highly competent local machine shop. I can see there is a larger diameter area about 3" long where the water pump resides. the top of this area is damaged as well so I am unsure of what the actual dimension should be. does any one have a good one they could measure for me so I can inform the machinist? if it makes any difference mine has tapered bearings and a pre-load pin on top of shaft



also, how do I determine if my engine is a 20 or 25"?

 

[Mi duckdown]

Re: drive shaft dimensions?

You have 3 inches. mic it, or the machinest can.

 

[68C15]

Re: drive shaft dimensions?

I should have been clearer. I am looking for the outside diameter of the water pump area. mine is so bad it is impossible to tell what it should be.