Need Help figuring out what bell housing to get

72dustervs said

I needed one myself , I found it on ebay , and just purchased a few days back , #3743859 is the one you need for O.D. Tranny ,,mine is going in my duster ,,unsure how an O.D. will perform but its been rebuilt so I hope it good for a street driver 340 , also the O.D. Tranny on mine takes the 26 spline on output shaft for drive shaft yoke instead of the 29/30 SPLINE

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That overdrive trans will like a rear gear between 3.73 and 4.10.
It's ratios are
3.09-1.67-1.00-.73od
With 3.91s your Road gears are;
12.08-6.53-3.91-2.85
That starter will let you idle a jumpy 340 around fairly slowly, and provides plenty of take-off grunt.
Second Road-gear is a pretty good ripper gear. Mine is 6.82 and is more than I need.
The Final Roadgear will get you about 65=2300; about as low an rpm as you dare go for getting enough cruise-timing. Mine cruises at 2240 with a different combo; and my timing is not quite enough for touring.But is close enough for, " a street driver"
Third gear is, well, third gear. As long as it's there you are good to go, lol.

If you already have something like 3.55s, or better, try them. 3.55s will get you a Second roadgear of 5.93. My 367 did not like that, but maybe your 340 will suffer it.
Anything less than a 5.93Roadgear will seem doggy in a 340 unless you really wind it out in First gear. Lots of Cylinder Pressure will help.
First gear is never a problem with a 3.09 gear in the box.