lost a gallon of oil- getting engine pulled

[brisenhoover]

Cummins called this afternoon., said they had the truck back together, just needed new gaskets on front cover and was headed for the dyno. Called back a couple hours later to tell me truck sounded funny, nixed the dyno, back in shop. They grabbed the bypass tube and said there was enough pressure to run an impact. Checked around and said number six was cold so they removed oil filter and cut in half to find it full of metal shavings. They said it was from having the pump turned up. Believe me, it's no 300 hp truck, but it DID a descent job pulling my 9000# trailer, but it wasn't like you couldn't feel it. It struggled up hills if I didn't hit them right, but I have an auto. Options are bore the #6 cylinder and ring it, or bore and sleeve it and they said they are going to send pump to Bosch to have it reset to factory specs or they won't warranty there work. Problem is the truck struggled to pull my 3500# pop up trailer when it was new. Now it will at least pull my 9000# trailer o.k. Can't believe that having it turned up like that would hurt this engine. The shop that did it has a real good reputation but Cummins said this isn't anywhere near the first truck thet have seen like this that this shop has "tuned up".
Not sure what to do. I've dumped thousands of $ in this truck to get it to pull somewhat descent and now the unstoppable Cummins died. The price of new trucks kills me. Now I have to dump thousands more in this and trade it off and spend tens of thousands on a new one. Don't want to do it. That's why I bought this truck new and payed it off thinking I could keep it for ever and pull just about whatever I wanted--Now back to square one or actually square -1. Any advice on motor?????

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1997 3500 4x4 McClain Diesel engine upgrades, B-D trans, 5" cat back, AFE air intake,7 track bars to date, one poorly designed front end compliments of Chrysler Corp.