Answers to your Questions


Do I really need TCM tuning?

It’s not absolutely necessary but it is highly recommended for proper shifting & taking into account the final drive ratio.

Our TCM tune addresses shift points, torque management and wide open throttle (WOT) RPM limits imposed by the TCM. The stock TCM tuning WOT shift point is at 3250 RPM because the stock power curve falls off before then.

The power band in the 4th-5th setting of our DSP-5 tune continues past that; By raising the part throttle and WOT shift points to accommodate the increase power band curve, it not only improves the ability to handle the power, protects the transmission and prevents slipping, but also increases the performance of the vehicle because it revs out higher and will improve the acceleration.

We also suggest the TransGo JR shift kit if you are running an Allison 6.

How long does it take to convert my harness?

Lead time on harness conversion is generally 3-4 weeks from the time it is received and checked in. At the time of check-in, the harness will be inspected and subject to additional charges (either mandatory or suggested) if there are any issues with wires, corrosion, pins or connectors.

I’m swapping the OEM electronic transfer to a manual shift case; Will that be a problem with either the DSP-5 or the TCM?

The conversion to manual case is not an issue and as long as you are using the factory style t-case the low range ratio should be the same as stock. (Although we can alter that ratio if another style case is used. If you want it to work correctly you will have to be sure to wire in the 4wd low activation sensor/switch to the TCM so that it will know when the truck has been shifted to low range or else it will put the trans in limp mode.

Do you offer a plug and play solution for late model chevy (Avalanche, Suburban, 1500)?

We do not support Duramax integration into late model vehicles (’96 and newer). However if you are planning on using aftermarket gauges we can create a proper standalone harness and the correct module calibrations for your application.  It will not run the OEM cluster in that truck.

If you are interested in our standalone harness you can follow our ordering guide, purchase your harness modification a well as the ECM and TCM tunes and we can certainly get it running and driving properly for you.

Can I use my factory gauges?

We do not support gauges, what we provide makes the engine run standalone. The factory gauges won’t work as they are. However all of this information and much more can be obtained through the OBD port with many available Can Bus gauge systems from companies like Dakota Digital and Speed Hut. We don’t sell them, what we offer is the CTS monitor, which can provide that information via OBD port.

Can I have my own tuner do my tuning? Will you leave the tunes unlocked?

We can only guarantee our system with our tuning. We have over 15 years experience with custom tuning Duramax diesels. We also have the most experience in the industry tuning Duramax drivetrains in swap vehicles. Tuning a late model GM truck that came with a Duramax from the factory can be much simpler than making it work correctly in a custom vehicle.

You can check out our parent company Pela Motorsports. Not only do we build our custom tunes in house but we also build race engines and complete custom vehicles. For this same reason, we don’t leave tune files unlocked to prevent resale of our proprietary software and eliminate being associated with 3rd parties modifications that lead to issues.

Additionally, we provide free tuning updates to all of our customers that buy their upgrade components from us.

Do you offer a standalone solution for an LGH with a 6L90E behind it?

At this time we do not offer an LGH/6L90E standalone solution. We do offer an LML Engine only and an LML \ Allison combination.

We have done several 4l80 and a few 6l90 behind earlier motors like LBZ and LMM. From these experiences we can confidently say that the trans is a significant limitation in the drivetrain capability. Due to the much lower torque capacity of these transmissions the engines must be significantly detuned from the factory truck calibration. Similarly, the operating systems for Vans/Cutaways/Ambulances/Bus’, are all specific to the configuration, making it more difficult.

We are currently testing a conversion harness that allows you to couple an LGH to an Allison with some modifications to the engine and should have results on this in the next month or so.

Do you support LGH?

The LGH is a detuned version of the LML engine and was offered in two configurations:

  1. LGH/Allison (cab and chassis trucks and fleet vehicles) These very closely resemble the LML Truck configuration and we do support these drivetrains in conversions.
  2. LGH/6l90 (vans, cutaways, busses) WE DO NOT SUPPORT THIS CONFIGURATION!!!

LML/LGH Swap Info

Do you have a standalone harness for an Allison 1000?

We don’t sell anything that would support that. You can contact CA Conversions to inquire about running the Allison transmission standalone.

Do you have a standalone harness solution for LM2 3.0L Duramax?

Tuning for LM2 are unsupported and we don’t sell anything that would support that as a standalone solution and have no plans to pursue that in the future. Closest option we offer is a standalone solution for the 2.8L LWN.


What is the order process?

We provide an introductory page to ordering with us; It explains our procedure, offers recommended items, quick link to the tune request form, and shipping information for your donor. Please review it for a better understanding of how to complete your order.

How do I place an Order?

Create and account, Log in and place your order. All projects are unique in their own way so someone from our company will be in touch with you typically within 24 hours to discuss your project and support your success.

Do I need an account to place an order?

We offer guest checkout but encourage our customers to register for our records and for easy of use on your next visit.

How Do I Track My Order?

Tracking Numbers are provided at the time of product shipment via email.

How Can I Cancel Or Change My Order?

Contact us for any questions or concerns with your order.

How Can I Return a Product?

All returns must receive an RMA number prior to shipping back to DmaxSwap.com in order to receive credit for their return. Most items are not eligible for return.


What Payment Methods Are Accepted?

Currently all major credit cards are excepted through Stripe and PayPal. A PayPal account is not required to process your cards.

Are there additional payment options

We will possibly accept checks and wire transfer. If you’d like to utilize these options, please contact us


What Shipping Methods Are Available?

Most products are shipped through UPS ground, faster shipping is available upon request. USPS service and FedEx are also available on request.

How quickly will you ship my order.

Shipping varies based on whether we are waiting for your part, have the request forms that may be necessary, have the item in stock, etc. We do our best to move on items/products that are available within 2 business days. We get excited about our orders, so we relate to how you are feeling. If you have any rush requests, please contact us

How Long Will It Take To Get My Package?

Shipping times are estimates at the time of item shipment and tracking numbers are provided when available.

Do You Ship Internationally?

Yes, international shipping is available. Additional fees apply.

Any unanswered questions? Contact Us