allison 5 speed auto

[sledhead]

The deal I had for the ht754 cr fell though so what 5 speed do you guys think would work the best ? I still want a 5 speed cr auto . How about a old school  ht 750 that work's off my transmission cable ? would I need a new tower or can the 4 speed tower I have now work ? Is the ht750 a good trans.                        thanks   dave 

[TomC]

HT754CR is the 5spd close ratio. Unless you find a HT750CR, the HT750 will basically be a 4 spd with a deep reduction low gear that should not be upshifted in motion. The HT740 is a really tough transmission-most Diesel drag and Bonneville trucks use this transmission. While it maybe a bit slower on a long hill, the HT740 has the same 1st, 2nd and final gear as the HT754CR. The only difference is the HT754CR has 3rd and 4th reduction replacing just 3rd gear on the HT740. Quite frankly-I don't believe it will make that much difference in performance-especially since we're just driving motorhomes. Good Luck, TomC

[HB of CJ]

FWIW.  May not matter in your application, but the four speed 740 is several inches shorter than the 5 speed.  Could make a difference in drive shaft length & U joint life.  The 740 I think is also cheaper? 

If memory serves, the older 740 was just as fast/quick in fire engines as the more expensive and longer 750.  Also the shorter length made it easier to use with admidships fire pump fire engines.  HB of CJ (old coot)

[Lin]

I do not know for sure but would guess that you would need a matched shifter to the transmission.  The shifters can require reasonable precision to manually shift into a specific gear.  I found this out when I installed a 740 shifter for my 647 4 speed Allison.  I could not get it to work right.  Not only was the throw on the shifter slightly different, but the shift lever at the transmission was slightly different too.

[Brian Diehl]

The 754CR requires its own specific shift tower.