I would think you could substite a '83.5-91 Vanagon radiator in place of your
diesel one without too much trouble.  Here are the parts you would need:
Radiator- $199
1- 251 121 083G hose- $77
1- N 901 666 01 hose- $30
That should be most of it.  The only thing I am not sure about is mounting as
the diesel radiator mounted to rubber bumper mounts and the newer radiator
mounts in holes in the body and lower supports.  I think Mark Drillock has
done this conversion, perhaps he has some input.  Prices above are for parts
from me.  

Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242