Penosin Leak...

[spsherm@ibm.net]

My new to me 87 5000CSTQ has a power steering/brake fuid leak.  The
previous owner notified me of this before the purchase; claiming the
rack needed to be replaced.  In driving on city streets I had not
noticed any loss of fluid or "wet" spots.  However after a few trips on
some dirt roads the leak is quite obvious, although too big to identify
an obvious source.

After ~ten miles on dirt roads the brake warning lite started to flash
intermittently.  When I stopped I nticed that the penosin level was a
tad below the min line (at the start of the trip it was 3/4 of the way
between max and min...

There is so much oil around the resevoir that it is hard to locate the
source of this leak.  It could have leaked out at the top of the res and
then down, or I suppose it could be coming from the rack (although I
can't see how oil from the rack would get up to the res.  Much of the
oil seems to be at the top of the resevoir (no the top was screwed in
tighly and properly) Although the gasket on the top of the res seemed
hard (if there even was one, I did not check, judging just from feel). 

Before I go off and throw in a new rack, I thought I'd check with this
group.  Is it common to get a fair amount of oil at the top of the res
with a rack leak?  Why would a rack leak be worse on bumpy dirt roads?  

My "educated" guess is that the oil is coming out of the top of the res.
Possibly a missing lid gasket.  This fits in well with the bumpy road
making it worse, throwing the oil around in there. I also noticed a
small hole in the lid where the end of the "float" assembly sticks thru
a bit.  Is this suppose to be open to air as it is on mine? 
  
Any comments on this.  Is there anywhere else in the system I should be
looking?  Or should I bite the bullet (wallet) and do the rack?

Thanks.