Yes Roger you're right the conversion to an SD709 is not a straight
drop in. Actually, researching adding my BEHR front AC has been very
enlightening. I have found out from Bentley (87.16) that the SD709 is
the recomended relplacement for the SD510, but requires several parts
to make it fit properly. Bus Depot happens to sell all of them:

Compressor SD709 $299.95
L-shaped A/C Piece 253260716A $73.26
Two o-ring seals 803260749B two @ $0.14
A/C pipe 253 260 708E $127.02
Two washers 431260749 two @ $1.67

The procedure is detailed in Bentley 87.16 so I won't repeat it here.

As you indicated in an earlier e-mail compressor capacity the SD510 is
a five piston ten cubic inch compressor whereas the SD709 is a seven
piston nine cubic inch compressor. The 709 is therefore less powerful
than the 510 but I am told by the Sanden factory rep that the SD709 is
considerably quieter.

I'm STILL trying to figure out if I have the double fin condenser, but
yes a second condenser might be an option.

Chris  

On 6/21/05, Roger Sisler <rogersisler2000@yahoo.com> wrote:
> Make sure you check the Bentley where it shows a modification to use the sd
> 709 instead of a 510,or you will be hot,bothered and broke.Ron is rubbing
> his hands and licking his chops over this. If you got a 709, you will have
> to adapt, or change the rear backing head,and/or hoses to use the 510. This
> is a swap of heads.It is not a simple exchange of compressors I have never
> worked on a post 85 vanagon a/c , so I cant say for sure.As for the
> condensor, dont know either.I think you can stick your fingers in the
> radiater and grill area and feel for 2 sections.What you really need (and
> me) is a duel condenser.Will the person who has done this and posted it
> (cant find it) step forward and tell us where we can find the details on
> this miricle of vanagon a/c.Thanks
>