my 90 dually swap

I am in the middle of a project, my 90 3500 dually originally had a 454 and 700r someone took it out and put a 350 in it, he passed away and his kids didn't want to finish it so I got it cheap, finished bolting it up and it wouldn't move ends up they swapped tranny also 4l80e out of a 93. I swapped tranny for a good old th400, every thing ran great for about 4 yrs then 350 got sick, I bought a 6.2 out of an 87 ton truck, but when I got it home I ran the numbers and it's an 84 c code. all egr crap was unhooked so I removed it all. now i'm trying to find a y pipe for it but no one lists it, muffler shop can make it no problem but I'll have to haul the truck to town. the manifold outlets are 2" with 2-3/4 flange holes where the later ones are 2-1/4" with 3" flange hole spacing. this truck has the 3" banks exhaust on it already and would like to keep it.

well I've decided to haul the truck to town when I get it running for exhaust, almost ready to fire up, am adding a gauge cluster because all the sensors work thru the ECM and I eliminated that. Which location would be best for tempature sender in the left front of head or right rear of intake there is senders in both locations.

You could use a stock gauge cluster if you found a diesel wiring harness and swap out the harness.
But the stock position is in the left front head.

I've been on this project since May but I was no hurry it's a project and I have more time than money, haha. had it running in June but the fuel kept running back to tank on me. I ended up replacing tank sending unit because I wasn't happy with my modification of original, I used the original two lines off the tank to where the fuel filter was in frame and put a check valve there. My son gave me some 3/8 stainless tubing he had and I made new lines up to engine, quite a job with a hand bender sure looks good though. started and ran about 3 min and died start right back up and die, pulled top off pump and it was full of little black junk, had to pull pump and found governor flex ring dissinagrated, so after a rebuild and reinstalled fired right up today now i have bleed lines leaking if aint one thing it's another.

Sounds like you are getting the gremlins sorted out

Be sure you have a good fuel filter in the system

I haven't had time to sit down and update, with harvest going on. But my 6.2 swap is running like a sewing machine, i haven't got a VRV for it yet but I just shift it manual, I need to get the right torque converter for it or I may get a 700R so I'll have overdrive but maybe next spring it's a work truck I don't do much highway miles. next thing is changing the front pulley's and convert to a serpatine belt.