If you are wanting to spend money to drop rpm at highway speeds what about a gear vendors over/under drive

You have to really want to spend money to go that route.

A re gear will work fine. Plus cummins get best mpg and power at 1800-2000. Don't give him silly ideas lol

The question is, are you going 60mph in the sweet spot or 75? I prefer my numerically higher gears myself. I'd rather just make more torque than play the gearing torque multiplication game.

OK I'm knew here an I have a question on my 98 12v. I'm thinking about rebuilding it. I know it has to b bored. So so question is what piston should I run in it. I do a lot of hauling. An what else do u suggest I should do with rest of motor as far as set up for towing.

Why does it have to be bored? I shudder to think what abuse a 12V would have to be subjected to for boring to be required.

First off I'm new to diesel. Don't know much about them yet but learning. I drove the truck with the #3 injector leaking bad I was only getting 6 to 8 mag out of it. So I pulled motor out to get tyranny fixed. So I went ahead a pulled head off to c if piston was burnt. As someone suggested. When head was off the #3 piston was as clean as a new one. So then I check cylinder for ware. It has some scratches u can fill. So now I'm stuck u what to really do.

both of my blocks needed a boring, one was too worn to bore actually. and if you want a tight engine boring is the best way to get that. re honing a standard size will bring the tolerances out. which can affect performance. depends how worn your engine is though, if you have like 0 wear then a hone will do. as for pistons it depends if you want to keep your stock injectors or not. i went with mahle power paks .020 over in my case. they are a performance piston but definitely don't break the bank. you will have to switch to a marine style injector 155 angle. if your just towing 370 marines would offer a good performance boost and match your new spray angle needs as well as being budget cheap apparently. i noticed a good weight difference between my stock pistons and the power pass which i assume will translate to a bit more power. as for the rest of the engine depends on your budget and what you actually plan to do with the engine. like chargers, intended power, what fuel set up you want to run, etc

OK I'll check into that. Another question is a buddy of mine has a older 1st gen 12v motor.
I'm wondering if that motor would work in mine. Can I change the p-pump an turbo off mine
Onto that one until I get mine rebuilt.

Absolutely.