<VV> powerglide questions (very basic, I hope)

[Chris]

I have a 61 Rampie with a powerglide.  I posted a few weeks ago about
problems with reverse.  Specifically, when I first start up, all gears,
forward and reverse, work perfectly.  As the vehicle warms up, I lose
reverse.  Several of you suggested running seafoam through it to loosen the
reverse piston.  I put in some seafoam today and then went on a 10 mile
drive.  This brought me through the forward gears multiple times.  When I
got home, I put it in reverse and left it running with the parking brake on
for 5 minutes.  Then, I did about 100 repetitions of putting it in reverse,
backing up, then putting in forward and pulling forward (about two car
lengths each way in my driveway).  I am getting it into reverse, and there
is enough reverse to overcome inertia on level ground, but my driveway then
goes up hill, and I can't get enough reverse to make it up the driveway.  

 

Anyway, I now feel I've run it enough to get whatever benefit I'm going to
get from the seafoam transmission stuff.  So I'm at the point of draining
and refilling the transmission.  This is where my questions come in.  

 

1)      There is a drain plug on the differential.  Does this drain both the
transmission and the differential?  I'm going to drip the pan anyway because
it leaks and needs sealed, so this is more curiosity than anything.

2)      While I have the pan off, is there anything I can adjust to give me
a more solid reverse?

3)      I understand that if I really want to change all of the fluid with
new, I will need to drain and refill the system a few times, as a lot of
fluid remains in the torque converter.  It seems I read to drain and refill
three times, running the car some and using all gears between each cycle.
Should I drop and clean the pan each time, or is it enough to do that once?
If I only do it once, should it be on the first cycle or the last?

4)      I'm not going to try to start a war here, but since this
transmission is not working perfectly, I decided to invest in synthetic
transmission fluid.  Any objections?

5)      Anything else I should do while I have the pan off?

 

Thanks everyone!

 

 

Chris