98 K3500 6.5 to LB7 swap help
Hello everyone
I'm currently building a truck it's a 1998 Chevrolet K3500 crew cab dually, it has the 6.5/4l80e combo which is ready to pull. I'm going with a 03 LB7 and allison trans. I currently have the harness getting reworked by Ken Wolkens for a stand alone and have the ECM and TCM already reflashed. Now the questions I have is what is all needed to integrate the LB7 to work with the GMT400 platform? I was told the starter relay will not work along with the gauges, what is all reguired to get the HVAC system working with the 98 hvac and the lb7? and what other problems will I have to figure out? thanks
1984 Chevy C70 Duramax Conversion
I received this email this morning, asking about an '80s square body conversion. Thought the discussion might be of value here.
Quote:
On 2021-04-15:
> I am considering doing a Duramax/Allison swap in my 1984 chev c70
> rollback it currently has a 427 5 speed,
>
> In has a cable driven speedometer I wondering what you have done to
> correct that ?
>
> Also does the Allison have the required hardware internally to drive a
> PTO , I know it has a cover plate but what about the internal gear
> required to drive the PTO
>
> If I do proceed with this project I will be purchasing you guide. Do
> you need to buy a wiring harness to make the conversion or does the
> guide show you how to modify the existing harness.
>
> Thanks In Advance
>
> Larry
>
>
Hi Larry,
I recommend you modify the dash of your 1984 truck to accept the new instrument panel. This will solve the speedometer problem and you'll gain a lot of functionality with the new powertrain. I also recommend you install the steering column that matches your engine package. This'll make it easier to shift the Allison, and it'll add a lot of functionality as well.
I know the early Allisons were setup to run a Power Take-Off, but I know the PTO was dropped a few years into production... before re-adding PTO in more recent models. So, to answer you, I don't know. I guess it sort of depends on model year, but I don't have a model year breakdown for the PTO.
For wiring harnesses, I recommend using the OE harness that matches/came with your engine package. New, these factory harnesses are about $600/ea (one for the engine and one for the Allison). One of the more expensive options is to acquire an aftermarket stripped-down harness that was designed for boats/RVs/basic conversions, but they require a specially programmed ECM/TCM and you'll lose most/all of the luxury features that came with GM's 2500/3500 trucks. Contact ppepower.com or bankspower.com for more info about their harnesses and ECM/TCM. Just remember that using an OE harness doesn't force you to use the extra features - you can pick and choose. The Conversion Guide we offer shows you how to install the OE harnesses, which is the least expensive option - no cost if it came with your engine/trans.
In the meantime, I'd suggest you spend some time with the following article that shows a 1987 Chevy C30 conversion...
https://www.thedieselpage.com/featur...Conversion.htm
Good luck,
Jim
2WD Transmission Crossmember Details
Recently, I've received a couple of requests for more information concerning a Duramax/Allison conversion in the 1990s 2 Wheel Drive (GMT400) body style trucks, asking whether the motor/engine mounts we offer would work. The answer is YES, but the transmission mount crossmember would need to be modified. Member Gordon Marks kindly sent me a couple images of his modified transmission crossmember, which explain how he accomplished his installation. Thanks Gordon!
Note: The factory 4WD GMT-400 (1990s) transmission crossmember works perfectly without modification in 4WD trucks. It appears the 2wd TRUCKS/SUVs have a somewhat different frame rail dimension when compared to the 4WD models. Mock-up the installation before committing to welding on the added material. You may find you need to adjust the height up/down a little to get ~ 3/4" clearance between the rear of the transmission and the transmission tunnel.
You can see from these photos that Gordon flipped the modified 2WD crossmember upside down and mounted it below the frame rails. Be sure to use lock-washers and thread locking compound just to be sure. Jim
https://www.thedieselpageforums.com/...9&d=1621261395
https://www.thedieselpageforums.com/...0&d=1621261446
'99 2500 6.5L to Duramax Conversion
I have a low mileage '99 Suburban with a 6.5. I saw the discussion of the conversion to Duramax, but it said it was intended for only the '88-'98 models. Am I correct in thinking that the difference would be in the dash-instrument cluster only?
Thanks