the hose size fittings are different between the two.

'throw in' a Subaru engine ?   It's far more involved than that to do a
really good job.
I spend 80 hours sometimes getting them really right and nice.

the bottles are not that expensive..
the easy thing is to buy the one you need now.
Bit complicated to make the 2.1 fit and work with your 1.9 cooling system.
Far more hassle than it is to spend say $ 30 on the correct bottle for now.

Scott
www.turbovans.com

----- Original Message -----
From: "Marc Hoelscher" <marc@HOELSCHER.CA>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, August 29, 2011 8:35 PM
Subject: Difference in expansion tanks?

> Hi all,
>
> I figured out why my '85 Westy ("Scooby") started dumping coolant on my
> driveway this week.  I thought it may have been an issue with the pressure
> cap, but it turns out it is a crack in the expansion tank itself.  This
> has
> created a dilemma that I'm hoping I can get some advice on...
>
> We bought a Subaru 2.5 and plan on throwing it in this winter.  Requires
> the
> 86-91 expansion tank (#025-121-403B).  The current 1.9 motor calls for the
> 83-85 expansion tank (#025-121-403A).  We can't see a difference from the
> images online between the two, and I was hoping that we could simply buy
> the
> 86-91 version and use it for the next few months until the motor swap.
> Anyone else know what the difference is between the two and if it is a big
> deal to use the newer version on the older motor?
>
> Thanks as always,
>
> Marc