Allison HT740 transmission types question

[Suprman]

I have a few Allison transmissions. They were intended for Oshkosh Hemtt use. They have a 24 bolt bell housing with approx 21 inch diameter pattern. Some are stamped HT740 and some are stamped HT740D. Both types have the same part number 23014539. The crates are all stamped with nsn 2520-01-257-3880. I called Allison, they said the part number is a standard HT740 4-speed automatic trans. Allison said they do not make a 740D, they make a 750DR which is a 5-speed with the first gear being very low. Some of the 740D's are rebuilt by Inland Detroit-Allison so I called them and they said yup its a 740D but couldnt give me any other info. Inland said the torque converter is a 498 type. Does anyone know is there is any difference between the two types and if there is a difference between the civ HT740 and the Hemmt HT740?
Thanks
Will

 

[Suprman]

No one has any insight into this?

 

[davo727]

Maybe the hemmit one is 20 times more special so you should ask 20 times as much as a civy one costs

 

[Suprman]

Thanks for that insightful comment.

 

[tony99561]

Several of the trucks in the (civilian) fleet shop I work at have the HT740DR this unit is indeed a 5 speed with 2nd gear start up and low gear 1st on manual selection.

 

[Suprman]

Very confusing since the 5-speed should be an HT750DR which has the 1st low gear but the 740 is only supposed to be a straight 4 speed.
Will

 

[Floridianson]

Will did you ever figure it out. My 915A2 has the HT740 and the HEMTT calls for the HT740D. From what I read the difference would be the torque converter. My 60 series engine goes to 2100rpm and the 8V in the HEMTT goes 1800 I believe. You still got any HT740's?
Found this so maybe show there were six different torque converters in 84.

 

[Shark Bait]

Will did you ever figure it out. My 915A2 has the HT740 and the HEMTT calls for the HT740D. From what I read the difference would be the torque converter. My 60 series engine goes to 2100rpm and the 8V in the HEMTT goes 1800 I believe. You still got any HT740's?
Found this so maybe show there were six different torque converters in 84.

If not, I've got a couple 740's that were overhauled by Raytheon in 2011 I believe. I can see if they have any numbers on them.

 

[simp5782]

I will bump this. The difference between the HT740 and the HT740D is the input torque rating. Which is higher on the D model. The D model also came in some crash truck variants up to 550hp. I came across one recently hooked to a C15.

 

[bpm4pte]

I have a few Allison transmissions. They were intended for Oshkosh Hemtt use. They have a 24 bolt bell housing with approx 21 inch diameter pattern. Some are stamped HT740 and some are stamped HT740D. Both types have the same part number 23014539. The crates are all stamped with nsn 2520-01-257-3880. I called Allison, they said the part number is a standard HT740 4-speed automatic trans. Allison said they do not make a 740D, they make a 750DR which is a 5-speed with the first gear being very low. Some of the 740D's are rebuilt by Inland Detroit-Allison so I called them and they said yup its a 740D but couldnt give me any other info. Inland said the torque converter is a 498 type. Does anyone know is there is any difference between the two types and if there is a difference between the civ HT740 and the Hemmt HT740?
Thanks
Will

Do you have any of the 740D transmissions for sale? I am looking for one.