[Vwdiesel] a2 Jetta rear suspension

[mikel]

Greetings fellow v-dubbers.

My Jetta has been being good to me for the last 3 or 4 months now, I now
have time to work on something besides the power unit.  I carry probably
about 100 -150 pounds in the trunk usually and it looks like it's
slightly squatting in the rear. Is there some cheap, easy and quick way
(2 out of 3 would be ok) to raise the load capacity?  I hauled 5
5-gallon buckets of gravel in the back seat the other day and it was
definitely maxed out.  

Any ideas as to stronger springs that would fit from any specific other
vehicle models?  The shocks are all in good shape still, all the way
around, but I don't know how old or what kind they are.

Thanks for any pointers,

Mike in NC