Fuel Pump Replacement, AGAIN!

ok, first time out, i figured, the truck has over 100,000 miles on it. fine, a pump can not last forever. put a new one on, get-r-done. now, just under a year later, i am doing this agian, and again on my dime. the pump i used was a genuine a-c delco pump. it is stamped right on the side of it. this time, i ordered another a-c delco pump, which is also stamped on the side. no problem there. but this time, i am comparing the oem pump, to the delco pump. they are definitly different. a-c delco is NOT the oem supplier of the pumps. my first guess, is that the oem pump, is most likely Delphi. since they seem to have taken over most of GM's parts and pieces. the part number between this pump and the first replacement pump differs, but i did not get them from the same place. so that does not concern me to much. the pump i will be installing today, is SUPPOSED to be for MANY GM cars and trucks for the year range that my Jimmy is in. so i feel confident that it is corrct for the application. of course, the proof is in the pudding, as they say. my big question is, is there some place that i can buy a Delphi replacement pump, without buying the entire cartridge? the cost difference is huge between just a pump and a puel pump assembly. and there is nothing wrong with the rest of the plastic or fuel sending unit. i REALLY HATE doing this job. but i fear it is going to be a once a year proposition. a school chum of my sons parents owned a Jimmy, and in 10 years, they put 8 pumps into it. he finaly got sick of removing the tank, and cut an acess hole in the cargo area! i have no intention of endangering my family by doing that! so the best soloution would be a better, longer lasting pump. i am thinking about a bosch pump if there is a next time. because of the German Engineering thing. if i can find a Delphi, i would rather do that, since i know it was meant for the vehicle. ideally, there will not be a next time. but i am usually not very lucky. so i am expecting the normal for me. in case it makes a difference, my Jimmy is a 2000 2 door, and does not have the robust fuel option. which i THINK is a good thing. since it seems to be scarce.

well, i got the new one in, and the truck up and running. i have an issue, that i do not know if it really is an issue. the fuel pump pressure gauge reads about 62psi, which is by itself fine. but, it is constantly fluctuating about 2psi very rapidly. the needle just bounces between 60 and 62 psi all the time the engine is running. when i shut it off, it sits at about 58psi, then it SLOWLY leaks down to around 45 psi in about 15 minutes. i do not know if the pressure relief valve is starting to have kittens, or if i maybe have an injector starting to go bad, or if this is actually normal. i do not remember if the needle bounced or not last time i checked the pressure. the last time i REMEMBER checking it was just before i replaced the fuel filter this spring. i am beginning to think mounting a real fuel pressure gauge inside the truck would be a really good thing to do. but i would somehow have to come up with a way to keep gasoline out of the interior. maybe i will mount one on the windsheild wiper panel. that way it would be outside, and i could still see it while driving.