If that is the case, what do I replace it with?

727.

A 727

You can buy a good convetor and HD pump gears , you'll need a new front pump more than likely .

If you want to stay with a 904 for less HP loss you could look for a 998 which was put behind the 360's , 5 clutch front and I think rear clutches and other HD parts .

Yes but trannys are cheaper.

See! Someone comes through. Now you need to shorten the drive shaft and move on to the next weakest link.

No way no how would I trade out a 904 for a 727 in this case, especially if you can do the work yourself. It's not hard..

Put the heavier duty pump gears in it, get a good converter and move on.

They put 727's behind 340 in the day because 904's were weak in comparison for the parts available. Not the case today. You don't have to be concerned with a front drum detonating on you with a 904... unlike the 727.

Anutter' vote furr keeping the 904. But I would FIRST check for any type of line pressure THEN pull the pan and see what kind of trash is at the bottom.

I had the same thing happen to be, the flex plate bolts pulled out of the convertor, some small damage, but a new flex plate or should I say the right one, fixed it. Motor would run and I could put it in park, but nothing else worked

not sure that it matters to you, but 727 weighs more. i rode in a 340 scamp with built 904 in it. it was a total screamer. personally, i prefer the 727.

Thanks, I did not realize that. I only dabble in 727 's because everything I work on/with has a big block.

I have run this transmission since 1994 when I bought the car and I don't know how long before I bought it had been run or even how it was run. It has never skipped a beat until I had my engine rebalanced because of vibration issues. I installed a B&M flexplate (that was the only mod I made except for the balance). Symptoms started right after that such as a slight rise in RPM and I would just hit the slapstick to the Drive position a little and it would cure the problem. It has done this a few times since spring when I put it back on the road. I attributed it to the modification I had done to the slapstick that TTI had said to do to get clearance for the headers. This may be just a coincidence, but now not so sure. Like I stated before the 904 has never given me any trouble until now and I have driven the car like I stole it since 94. I just have been thinking about the whole thing and the only thing that comes to mind is the B&M flexplate may not be letting the TQ engage the front pump properly. Comments welcome.

I haven't got the tranny out yet to see what's wrong and probably won't for at least a week, when I do I'll post what I find.

OK, the transmission is out now I can't get the torque converter off. It comes out about 1-2" then a thud and won't come off the tranny shaft. What's up with that? Should I force it? I tried to pry slightly with a couple of screwdrivers.

You are going to have to get physical with it and pry it off. One of the ways we use to get stuck axles out was to bolt a length of chain to the studs and throw the excess chain out away from the end of the axle.It made the chain work like a big slide hammer.