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I have a very large Allison automatic that came from behind a 4bta in a bread truck, 2 wheel drive, anyone know which ones came on the 4bt? its a 4 speed

thanks
 

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thanks, any easy way to tell the difference? do they use the same adapter to the engine?
Yup, they use the same `dapter. it should be an SAE#3. there`s a tag on the pass. side, rear, down near the pan flange that should tell you if it`s a 542 or 545. they look the same, biggest difference is the gear spread.:)
 

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Yup, they use the same `dapter. it should be an SAE#3. there`s a tag on the pass. side, rear, down near the pan flange that should tell you if it`s a 542 or 545. they look the same, biggest difference is the gear spread.:)

I may be mistaken, but I'm going on the specs I have seen, and there is no difference in the gear spread. Additionally, they have identical power ratings.

The one difference that I have been able to pin down, is that the pan depth is 5.3" on the 545, and 3.8" on the 542. I can't help but think that there must be some additional difference, but I have been unable to find it. There is a GVW rating difference between the two: 545-30,000lbs / 542-22,500lbs, that would seem to indicate some mechanical changes in addition simple fluid capacity, but I have no idea what they might be. Perhaps different numbers of clutches in the packs.
 

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Their spec sheet shows there is an optional input retarder available with the deep pan option . I never heard of that on those models................but it was available on the 50s/70s vintage MT 40/41/42 , and Ht70 of that vintage ,plus the HT 740/750s of 70/90s vintage . In put retarders are not worth the money !
 
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