454 to 6.5 TD swap

I know what you're all thinking, why would I neuter my truck and yank the 454 out? It's going to be transplanted in a square at some point in the future, it's not forgotten
Ive recently acquired a totaled 1993 K2500 6.5 NV4500 truck with 136k miles for a steal, and I'm wanting to drop the drivetrain in my 1995 K3500 454 4L80E. I've been daily driving the truck for the past year and 8mpg is starting to hurt a little more. What all will need to be modified to make the mechanical 6.5 work with the 454 wiring? I'm perfectly ok if I have to add a toggle on the dash for glowplugs/fuel cutoff solenoid. My main concerns is swapping in the NV4500, making the factory 95+ gauges work. Is the VSS on the nv4500 plug and play with the 4L80E wiring harness or will it need to be modified? I've been digging through the wiring harnesses on both trucks and it looks like oil sending unit and the temp sending units are all plug and play. as for the RPM gauge, on the diesel the RPM reference is from the alternator, correct? I'm also aware I am going to have to find the correct driveshafts or take it to a driveline shop since the donor truck is missing them. As for the clutch pedal/slave cylinder setup, will the full setup out of the 93 work in the 95 or will I need to source a different setup.
If anyone has done something similar to what I'm trying to accomplish or may have a source for a factory 95+ 6.5 harness, doesn't matter if it's a electrical injection pump let me know what ya got.

Interesting since I have the 6.5 TD
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Curious if there is another reason you are only getting 8mpg. I am daily driving a 97 with the 454, 4l80e, 4:10s, 6" lift and 285/75r17s (34") tires and I'm getting close to 11mpg hand calculated. Granted over half of my 17mile commute is 65mph.

I don't think it's all that crazy though I would probably do a 6bt/nv4500 with a rotary pump myself because of the aftermarket support and the fact those motors regularly get close to 20mpg in 3/4 ton trucks.

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Just to simplify things, i would take as much as you can from the donor truck and keep your harness from your 454 and 4l80e together and rob the whole thing from the 6.5. Sure you will have some wiring with the gauges and dash but i feel like that would probably be the better route.

ZRoe said:

Curious if there is another reason you are only getting 8mpg. I am daily driving a 97 with the 454, 4l80e, 4:10s, 6" lift and 285/75r17s (34") tires and I'm getting close to 11mpg hand calculated. Granted over half of my 17mile commute is 65mph.

I don't think it's all that crazy though I would probably do a 6bt/nv4500 with a rotary pump myself because of the aftermarket support and the fact those motors regularly get close to 20mpg in 3/4 ton trucks.

Sent from my moto e5 supra using Tapatalk

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Your 97 is a Vortec, makes all the difference in fuel mileage alone right there

Will Ferrell said:

Your 97 is a Vortec, makes all the difference in fuel mileage alone right there

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My TBI was better on fuel than my Vortec.

I have towed with a 454 TBI. At 16,000 lbs total weight it would still get 10.5 mpg. 454/4L80E and 4.10s.

8mpg means the truck has problems. Either needs a tune up, has leaking injectors, low fuel pressure, retarded timing, a plugged cat or brakes dragging.

L31MaxExpress said:

My TBI was better on fuel than my Vortec.

I have towed with a 454 TBI. At 16,000 lbs total weight it would still get 10.5 mpg. 454/4L80E and 4.10s.

8mpg means the truck has problems. Either needs a tune up, has leaking injectors, low fuel pressure, retarded timing, a plugged cat or brakes dragging.

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My 91 2500 454/4L80e got 15mpg Highway 10 towing anything, my 95 has at best seen 10 if I keep it at 70 or below. The 91 didn’t care about speed. I’ve got new injectors in the 95, full tuneup and a new fuel pump. No cats. Brakes aren’t dragging, actually they barely work right now...

Madscientist said:

Just to simplify things, i would take as much as you can from the donor truck and keep your harness from your 454 and 4l80e together and rob the whole thing from the 6.5. Sure you will have some wiring with the gauges and dash but i feel like that would probably be the better route.

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Has anyone succesfully got everything from a 88-94 wiring harness to work with the 95+ dash correctly before?

‘95 is more similar to a ‘94 than you may think.

Will Ferrell said:

Has anyone succesfully got everything from a 88-94 wiring harness to work with the 95+ dash correctly before?

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People do dash swaps all the time. I dont see how it would be any different