Sorry I don't have a part number for the tranny cooler.

Summit Racing has a comparable unit to the B&M one I installed (got mine used off of ebay).  You can see it here...

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2DG4960A&N=4294888847+115&autoview=sku

As to installation:

The fittings are 12mm 1.5 pitch, which is the same as the bolts that hold the old water cooler. A mechanic or wrecker can help you if you want to go the used route.  Look for the (banjo fittings) that come off the gas tank lines on just about any Fox, Jetta, BMW...they're probably all the same. You'll have to unhook the tranny from the mount to get at the original water  cooler. 

You'll need about 25' of 3/8" hose rated for the application depending on where you'll mount the tranny cooler.  On my first van I mounted in the passenger side plenum that runs just outside the frame rail.  I mounted the cooler at a 45 degree angle and fashioned a steel scoop to direct air to it while the vehicle was moving.
The second time around I mounted the cooler right on top of the auto transaxle.  I prefer that location.

If you want new parts you still have a choice to make.  You can drill and carefully tap the threads of the transmission to a standard SAE thread or you can leave them metric and pick up some fittings to get you to 3/8" tranny oil hose.
Below I've listed some part numbers you can find online to help you decide.

You'll need two fittings that screw into the transaxle body like these.....

http://fittingsandadapters.stores.yahoo.net/maljictomalm.html

Male Metric Adapter

Part Number 	816MM-5-12
Male JIC 	5/16
JIC ThreadSize	1/2-20
Male Metric 	M12x1.5
Sale Price 	 $15.60 

OR
 
http://store.summitracing.com/partdetail.asp?autofilter=1&part=AER-FBM2246&N=400274+304784&autoview=sku

Part Number 	AER-FBM2246  
Type	 Fitting Straight
Desc	 AN Flare to Metric -6 AN to 12mm x 1.5 Male
Metal	 Aluminum
Color	 Blue
Price	 Each $9.95


You'll need two fittings that take your adapter to the 3/8" hose like these.....


http://store.yahoo.com/fittingsandadapters/puslochosto9.html

Push Lock Hose To 90° Female JIC (Swivel)(Steel) 

Part Number 	JF-90-6-6
Hose I.D. 	3/8
Female JIC 	3/8
Female JIC Thread Size	9/16-18
Sale Price 	 $6.47 



Instructions for installation of auto trans cooler

Remove the old vanagon auto trans cooler by removing the two bolts that secure it to the transaxle.
Have a rag ready to catch the auto trans fluid which WILL make a mess.
Cap or join the two coolant hoses that feed through the cooler.
Screw the 2 smallcar brass ell fittings (12mm diameter x1.5 thread pitch) into the holes left by removal of the old cooler.
Tighten the ells so that they face up to 12 oclock
Install a length of 3/8" transmission cooler hose to the installed ells
Tighten the hose lengths to the barb on the installed ells with stainless steel band clamps
Choose a location for your cooler and secure the cooler
Route your 3/8" hoses from the transmission connection to the cooler connections (direction doesn't matter)
Use care to route your hoses so that they do not abrade/rub against other parts and will not be pinched by suspension components.
Secure the hose connections to the cooler using stainless steel band clamps.
Fill your transaxle with an appropriate automatic transmission fluid.  Start the engine, shift slowly through the gears, stop the engine and check the fluid.