FMTV M1078A0. Transmission Swaps

[Lugnuts]

I am presently frustrated by not having knowledge of Allison MD3070PT Transmissions like I would like so that leaves me with turning to y'all for my information but I think this might be profitable for now and time to come. I did not find the information on a search so maybe my wording was not correct. If in fact I am in error and there is information on this subject please direct me. Thank you.
I have two transmissions, in one, the clutches are gone because of water and the back case got shattered and I have another transmission in what appears to be good shape from a unit that was rolled. The oil was very clean and it was working when it came to an early demise. Now I called Weller transmission with the serial numbers and it was stated the they were the same in mechanical parts BUT the valve bodies were different. One valve body was an 81 series and one was the 82 series. I probed for what that meant to me and though the fellow could give me some indications what it meant, he could not get specific.
It may have to do with different engines, or speeds, but it doesn't seem to matter as far as the mechanical end is concerned..So I am told but don't know. Yes I am looking for clarification. Can the Mechanical end with good clutches be used by "merely" swapping valve bodies? Do I need to abort the whole issue? Is the wire harness still the same with plug? Just change the Key Pad?
That's right - HELP!!!
I am almost sure these questions been asked before and someone has the answers and they most likely will be asked again!!
Thank you, Lugnuts

 

[NDT]

What year model truck is the blown transmission out of and what year model is the rolled transmission out of?

 

[Lugnuts]

What year model truck is the blown transmission out of and what year model is the rolled transmission out of?

Bad transmission is out of a 11/97 and good transmission is out of a 10/98

 

[NDT]

That helps. The factory changeover from WTEC 2 to WTEC 3 happened around January 1998. So that is the difference you are challenged with. I would NOT change transmission internals. I would upgrade the harness and controller and VIM.
Rumor has it there was a kit to install a 3 transmission into a 2 truck but I don’t think those are findable.
Other ideas folks?

 

[Ronmar]

there is a section in the tech manual going over proper configuration for transmission changeouts. I think it is in the 34-1 or 34-2 manual which you can get in the manuals section on this site, but it has been a while since i went over it. it was based on serial numbers if i recall. but as NDT alluded to it has to do with the valve body interfacing with the controller.

I think the basic transmission housings in the 3000 series are the same but the valve body/control module, wire harness and TCU and dash harness are/must be a matched set...

On the A0 WTEC2 the TCU is in with the keypad and it has a Vehicle Interface Module under the passenger dash. As mentioned in 98 they started introducing the WTEC3 which has the TCU under the passenger dash where the VIM was located, a remote keypad in the drivers dash and they used 4 relays in the power panel to provide the VIM functions(neutral start, reverse, diff-lock request/power divider and PTO on).

 

[simp5782]

I've got a 1088 that is a 3116,WTEC 3 truck.

Transmission has been sold. TCM & keypad are sold as well

But I've got the frame harness and all the cab harness if needed or I can sell you the whole cab with everything

 

[Lugnuts]

That helps. The factory changeover from WTEC 2 to WTEC 3 happened around January 1998. So that is the difference you are challenged with. I would NOT change transmission internals. I would upgrade the harness and controller and VIM.
Rumor has it there was a kit to install a 3 transmission into a 2 truck but I don’t think those are findable.
Other ideas folks?

Is it verifiable which Generation it is. I do not have the keypad and I haven't looked at the VIM. Not that I am challenging you but is the valve body a swap that can be made and expect it to work properly? Is Gen3 better than Gen2? Can it be verified by the numbers? Is there a secret branch of Allison that can help you on these matters? Does anybody really know what time it is, does annybody really care? (Just an old Chicago tune I thought I would throw in there free of charge)

 

[Ronmar]

Go to the home page on this group, under manuals find the LMTV M1078A0 manual set available there. Download TM 9-2320-365-34-2 from that group(download them all).

various bits and differences listed by trans S/N in the transmission change-out procedures, but look at Appendix H. it has a chart showing what is necessary to mix and match components based on trans serial number.

you may also run into a difference in flywheel-flex plate interface as there were 2 styes used, again based on trans S/N...

 

[Lugnuts]

Go to the home page on this group, under manuals find the LMTV M1078A0 manual set available there. Download TM 9-2320-365-34-2 from that group(download them all).

various bits and differences listed by trans S/N in the transmission change-out procedures, but look at Appendix H. it has a chart showing what is necessary to mix and match components based on trans serial number.

you may also run into a difference in flywheel-flex plate interface as there were 2 styes used, again based on trans S/N...

Thank you. Didn't know such a thing existed but I do now. Thank you

 

[Lugnuts]

Thank you. Didn't know such a thing existed but I do now. Thank you

So I found Appendix H and I still have to explore the information that is being presented but I am writing to say that if anyone has spare time to look at it, it would be very profitable. At first glance there are alot of variations in what you can use. The appendix H is at the end of the book right before the electrical schematics. No page numbers, Just Appendix H. Thank you