oil pump driveshaft ???'s

I need to order a new oil pump driveshaft. Summit sells two.
arp and milodon. the arp is a bit less spendy, just $3, but it gives a much more detailed description. they are both chromemoly, I was told there was a titanium one that could be had.

also, the arp is bigger in diameter than the stock unit.
How does that affect install. Wouldn't you have to force it onto the distributor.

and finally, how are these things held in place on sn95's. do you just drop it in and use a set screw or does it screw into place or what. I am pulling the motor to replace this on my own, I hope. so I need as much info as I can get.

my last one just sherred off. there was about an inch of it inside the dist shaft. I lost oil pressure so I tore it apart and that is what I found. Any ideas on why this would break. Was I 180 off on the distributor install or what. TOO much timing. I hadn't even had it running long enough to check it.

It started fine, and idled good. just no oil pressure all of a sudden.

thanks for any help you can give

what could cause it to lock up. this is a fresh built motor with absolutely no mileage.

If I pop this cover off, what should I be looking for?

This will be my first experience with this, I had the shortblock prepped by my machine shop.

I will probably just get a ford shaft cuz I don't want to have to modify the msd I just got.

when I get it put back together should I start it with the spout connector off or what should I do about the timing issue right away on a first startup??

thanks