Yes, you're probly correct to suspect the front pump. The problem is either; #1 worn pump,in reverse, the line pressures are 2-3 times higher than any forward gears. The extra pressure demand taxes a worn pump to the point it can't output enough fluid volume. #2 worn touque converter or input shaft, causing a cross leakage between the two. #3 The transmission is badly overheating due to a plugged cooler system. This is VERY common with lock-up torque converters, as the clutch lining in the converter can fail,plugging the cooling lines,or cooler. I'm bumping up some of my old posts for you.

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V8?? We don't need no stink'n V8!!

Could it just be that the line pressure is not adjusted properly? I have ruled out torque converter failure since it operates perfectly in all forward gears even when hot.

HARV

I am new here and was going through the current threads.
I started reading this thread,

http://www.slantsix.org/forum/viewtopic.php?t=43924

right here on this same page and immediately thought of you.
Do you know the year of your trans?
He states 78's and 79's were known for your very symptom.

Very interesting, as I did not know Lock-Up was available in these years.

When this reverse lock-up occured, was neutral acting normally or was there any tendency to creep forward in neutral?

I was just wondering, would the 86 pump work in the 78 or 79 trans? I thought about making a Frankenstein transmission and using the pump (which I know to be good) in the other trans to see if the problem is actually the pump not putting out enough pressure. Also, should I change the lock up module on the valve body to the 86 to help alleviate the problem? I am going for broke here. The 727 that I installed seems to be wearing a little faster than I wanted it to.

HARV