Oil pump shaft issue: figured it out

[smsag04]

I'm trying to replace the oil pump in my Mustang. It's got an engine from 1963. I got the Melling M-65 oil pump which appears to be the correct pump, but the shaft that came with it is different than the shaft that came out of my car. Both are 1/4" shafts, but the one that was in my car is 4.5" long while the one that came new with the pump is 3" long. Does anyone know why there is a difference? I don't want to reuse the old shaft because the corners are starting to round off.

 

[kukm66]

Is this an M65a or a M65B?

What about the old one?

 

[smsag04]

It's just M-65, no A or B. On the old shaft the corners are starting to round off. I'm sure it would work, but I'd rather put it back together with new parts.

 

[kukm66]

These are the shaft sizes that I have seen:

2 15/16" 1/4 shaft
4 1/2" 1/4 shaft M65A
5 1/8" 5/16 shaft M65B

The 4 1/2" came from a 170 with a 1/4" hex shaft
The 5 1/8" came from a 200 with a 5/16" hex shaft

I am not sure about the small one

 

[smsag04]

Got it figured out. On my old pump the shaft went further into the pump body. On the new pump, the shaft doesn't extend as far into the pump so the shaft doesn't have to be as long.