We are in the process of replacing a 6.2 / 3L80 with a 6.5TD / 4L80, and there are many modifications that are required. This post is solely about driveshaft lengths. Measurements are from center-of-cup to center-of-cup.
Due to unforeseen issues, we have been unable to update this site since May, 2019. There has been considerable more information and pictures gathered, and we intend to update this website fully by the end of October.
We are now in the process of updating the final information from the M1038, and are currently in the process of repowering an M998 with a 6.5TD removed from an M1114.
Please feel free to email us with any comments or requests.
It took a lot more fiberglass work than expected, but it turned out nice. We were going to install LED headlights, but we may end up installing sealed beam for the time being. All the blackout lights were masked off and painted. By using pinstripe tape, we were able to have sharp lines between the lenses and the housing.
On Thursday, April 28, 2019, Michael Grundman helped bleed out the fuel system by pressurizing the tank. After successfully getting fuel out of the filter drain, and then the bleed valve on top of the main filter, we gave the engine a “bump,” and it lit right up.
The glow plugs were not attached, and ambient temperature was around 65 degrees, but we were happy that it lit up that nicely. This video was taken several days later. You can hear the “click” of the control box, and the engine light up instantly.
The main task was transferring all of the hardware from the other fuel tank to the new fuel tank. We used Gasqacinch on the rubber gasket for an additional level of leak protection, and because it permits easy removal of the gasket in the future.
We learned that it is better to install the vent fittings on the tank prior to installation. Additionally, it would have also been beneficial to install the front heat shield prior to installation. However, both of these tasks can be completed with the tank mounted.
After receiving and unboxing our newly arrived 5582606 fuel tank, we decided to do a side-by-side comparison of them. As visible from the picture above, the later model tank is distinctly larger.
Visible on the rear of the tank is the cut-out allowed for the drive line parking brake.
Also of note is that the tank skidplate does not fit the older-style tank. Although we could have cut and used a brake to rebend it, we will store it for a future project. Additionally, it is clear that removal of the driveline would not be required to install or drop the older-style tank because of its reduced size.
As explained in an earlier post, we unknowingly attempted to install a later model fuel tank into an early model HMMWV. And despite difficulty in locating the correct tank, we were able to. It arrived today, and we intend to install it in the next few days.
As we install this tank, we will attempt to document and post any differences between this main fuel tank and the early tank.
We had purchased a fuel tank for our M1038, as well as the missing straps, fuel level sender and other pertinent parts, and were ready for installation.
We were unaware, however, that the jumper between the fuel tank and the wiring harness was missing. So, using the correct Prestolite wire, wiring ends, and PET loom, we fabricated a replacement jumper. (Ensuring that it was made to military specifications).
UPDATE 3/ 24/2019: We fabricated the jumper at a 36″ length. As it turned out, the length could have easily also be made at 18″-24″ length. As it turned out, we cable-tied the excess to the fuel tank vent tube near the crossmember where the jumper connects to the harness. We suspect that should we have to remove the tank in the future, the extra length will prove “slack” to permit us to lower the tank without having to disconnect the jumper from the harness.
We were ready to install. Or so we thought. Even after removing the driveline, we found that we could not physically fit the tank into the area, as it hit the emergency brake caliper, rotor, and bracket.
We were simply unaware there was more than one main fuel tank. Our tank 2910-01-447-3911  carries part number 12460105, and is easily located. As it turns out, we should have verified application through the UOC (Usable On Code) found in the parts TM in the far right side under description.
The UOC for a M998 is H13, whereas the UOC for a M1038 is H14. For practical purposes (other than differences between having a winch or not) either code would be accurate.
As it turned out, the NSN for the tank we had did not have the correct UOC, and we found the tank we required was part number 5582606, with no NSN provided for a part number. We simply had the wrong tank.
Through further research, we were able to identify a serial number split from 1 thru 44824, which uses the brake mounted against the rear differential on the driveshaft side. 2530-01-174-7441 .
We are well aware of operator complaints regarding this parking brake, but have found to often that operators attempt to adjust the brake from the brake handle adjustment (which is meant only to adjust for slack in the cable), and not properly adjust the brake from the caliper adjustment. We purposely chose to maintain this brake system because of our unit’s 4 digit serial number for historical purposes.
However, as noted above, we were completely unaware that maintaining this brake would require a fuel tank of limited availability.
For our M1038, we obtained a mid-series control box, and a corresponding controller. The control box was in unused condition, and its connectors show indications that it has never been connected.
We located a controller that corresponds to the controller, but it had sustained some cosmetic damage.
Information on this controller 19207ASSY12446779 is scant. From what we can determine it was used on the M1113, and is similar to what was used on the M1114. (The M1113 used studs, as on this box, while the M1114 was threaded where the studs are).
It may also be referred to as a “silver label.” To make it clear, these are not EESS boxes. These boxes have been used on trucks up to the m115x, and are the generation between the old yellow/green label ones & the EESS. They are apparently a generation newer than the yellow label control boxes.
We have been cautioned that the operation of this box may make the “wait light” fail to light at higher ambient temperatures, but that is simply because it is not necessary to cycle the glow plugs.
Additionally, we have been cautioned that should a control box fail, there is a possibility that a vehicle fire may result. We will be installing a battery cut-off and will be testing the box before sending the vehicle out the door to reduce the potential for vehicle fire.
We have read good reviews on these boxes and that they are relatively reliable. However, if we note any issues we will reach out to an appropriate vendor for a newer generation control box and controller.