I have a 71 dodge dart that has a 440 ci engine /I had the 727 trans built with all the good stuff... Now I can't get a steady 3rd shift,It drags when it shifts /almost like its down shifting into second again..only for a second than all is fine .I have adjusted bands and detent cable several different times to no avail ...any suggestions whould be greatly appreciated...

It sounds a little like the common 2-3 upshift rev problem to me, but I'm not sure why it's doing that if you've done these adjustments....
What stall converter are you using, not that it should make any difference, but maybe?
was the valve body assembled correctly?
What's the fluid pressure like? Is the trans cooler (radiator or external) clogged?

give me a little more to go on. Could be normal?

Slantsixness

Is this when you're letting it shift by itself, or shifting manually? Or does it do this either way?

It sounds a little like the common 2-3 upshift rev problem to me, but I'm not sure why it's doing that if you've done these adjustments....
What stall converter are you using, not that it should make any difference, but maybe?
was the valve body assembled correctly?
What's the fluid pressure like? Is the trans cooler (radiator or external) clogged?

give me a little more to go on. Could be normal?

Slantsixness
new radiator with trans cooler/ new made trans cooler lines/3400 stall converter/ I have not checked pressure yet. Trans builder thinks I need bigger trans lines but I have my doubts , shifts the same at all speeds and doesn't matter if I shift manually or not????? thanks

So if you're doing a good 4500 rpm or something and you shift from 2nd into D, like slapsticking it, it doesn't shift even?

When getting into it hard and shifting manually I don't feel the erractic shift,but it really doesn't feel like a firm shift

2-3 upshift on a 727 is usually a lot softer than the 1-2 shift, it just seems to happen that way from design.

Some problems I have seen that cause this to be predominant and too noticeable:

1.Fluid level too high (simple, but it happens)
2. Incorrect filter (put on incorrectly)
3. Fluid starvation (trans pan too small, use a deep one and a filter spacer)
4. pressure leaks in valve body (replace)
5. Wrong springs in servo(s).

Now these aren't normal problems, but sometimes they are overlooked, because the trans tech is in a hurry, or just missed it.

Your troubles could be solved using a small block 727 valve body. There are small differences, check your parts book!

Hope I helped!

Slantsixness