MD3070 vs 3700sp (Allison 7speed Tranny in these trucks)

[coachgeo]

There was a model number change. from MD3070 to 3700sp. The Transfercase bolted on the end also got a model number change. Allison rep told me there was no difference in TCase as far as he knew but could not offer more since it is still under military contract.

I suspect one change may be that this model has different ECU and connections for ECU thinking it may be the upgraded version designed to talk with the ECU of the engine; where the first model (MD3070) was used with trucks that had no engine ECU. But this is just a guess

Does anyone know if this change represents any internal, computer or??? between the two models?

 

[Keith Knight]

I don't have any info on the 3700sp, but I do have experience with the MD3070. I own a 2003 M1078A1 with the MD3070 transmission and my original transmission died and in the process of getting a used replacement I found that the MD3070 does have variations mostly with the internal wire harness and solenoids. My M1078 has the 3126B engine which has an ECU for the engine and an updated ECU for the Transmission. I had use the transmission serial number to verify compatibility.

 

[Lmtv772]

I forgot to ask Keith. How did that transmission work for you? Was there any issues with that one bolt we marred up when we removed it from the parts MTV?

 

[Keith Knight]

So far so good its running ATF DEXIII. I've put about 600 miles on it. the hole was good after running a tap through it.

 

[mkcoen]

Oof! That does not look like a fun job. I hope mine lasts as long as I do.

 

[Lmtv772]

Btw Keith, outstanding job one the transmission rig

 

[spankybear]

So far so good its running ATF DEXIII. I've put about 600 miles on it. the hole was good after running a tap through it.
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Thanks for the picturtes/.