Ahhhh, finally. 
I have been having the EXACT symptoms slagathor1 has in 
my 1983 M41 (gl 2wd, 150k+ miles). 
I had read a post somewhere here (archive?) that a fellow 
had the exact same model, and problem, had changed the 
modulator with no luck. He said he was going to do the gov 
next. He never came back!!! (Did it fix or did he replace the 
whole mess?) 
I have purchased a new drive for the gov ($12 from a national 
place that's hq here in Pittsburgh.) 
Was wondering if I could use a steel drive gear (turbo) on 
a non-turbo 2wd trans? Was unsure so I got the plastic, 
after as far as I know it's never been replaced before and 
if I get anywhere near 150,000 miles on the new one that's 
just fine with me! ;-) 
In any case, now that I have confirmation that it's a gov 
problem, I will do it tomorrow! 
Hopefully it won't eat the new one!  
  
Btw, on the rebuild archive I saw and everywhere else, 
it never mentions that (at least on my gl) all you have to 
do is remove the spare tire and reach into the area of the 
AT and the gov cover is right there above the CAT. 
(would have jumped into the job earlier if I knew that) 
  
If this does fix it I think I'll also flush the fluid etc.