I had a SD510 compressor in my van, but I'm replacing it with a SD709
as per Bentley 87.16. The SD510 compressor is mated to the 25326063
"D" Receiver Drier:

http://www.vanagain.com/images/S_253260633d.jpg

So when I'm replacing it do I use the "D" again (which is recommended
for the SD510), or now that I am dropping in a SD709 do I use the
25326063 "E" (which is recommended for the SD709):

http://www.vanagain.com/images/253260633e.jpg

The outward difference appears to be the slight offset of the "D" from
center, but the line to it is flexible so I'm sure it would reach. The
"D" costs more than double what the "E" does. What do dryers do
anyway? Is it a capacity issue or a fitment issue?

Any thoughts?
Chris