If you get a LPOP get the melling and get it at Advanced Auto. First look online and find a coupon code for around 25-40% off. You have to look at the list price of the Melling pump and then find the coupon code that fits it. Then do a online order but check off that you want to pick up in store and check off your local store that has one in stock or if they have to order it so be it or find a store that has one within driving distance. This will allow you to get the full online coupon discount and still be able to pick it up right way and no shipping costs. If you do a search on here for my name and melling pump or advanced auto I lay it all out in detail about a year ago. I think with coupon it cost me $60? maybe less I can not recall now but still cheaper that ANYWHERE else that listed a price.
When you install the pump coat it with some grease as that will help it seal and pump when it initially spins. While you at Advanced or any of those stores that loan tools get the loaner harmonic balancer puller set and the fan bolt wrench set.
While you have the pump out check the front cover mating surface for the pump carefully for any wear. galling or groves etc. Hopefully its OK and the pump is just worn and dead.
Do not use a air gun to try and tq the HB bolt it can cause the seal to leak sometimes. Lock up the fly wheel or otherwise prevent the engine from turning over so you can get the proper TQ. If there are any other upgrades maintenance that require the fan etc to be pulled now would be a good time to do while you have it pulled apart.
It really is not a hard job and should take a weekend afternoon to do. At a casual but steady with a few cold ones sort of pace 3-4hrs. Do it a few times and half that. Such as when you forget something and have to redo it. Its amazing how fast you can get at things when you do that a few times. LOL
Here is that post where I put the info on how to purchase online. I ended up getting the pump for $49 list was $79. Well worth taking 10 min online.
http://powerstrokearmy.com/forums/showthread.php?t=23161 go to my post which is post #15 for the ordering info in that thread. That entire thread maybe of some help for you as it deals with LPOP with pics. Please give me credit if when you sign up with Advanced to order as it will get me a discount but it also gets you another $40 discount on your next purchase IIRC and it still the way it was. That is in that post near the end as well with a straight link for it.
There is also some info about the pressure regulator that is in the oil filter base unit part of the oil cooler. Just in case the LPOP checks out.
Here is a how to sheet I had for the LPOP install etc. It may be of some help to you:
