Ben,
the two hoses come through the bulkhead from the heater side by side. The one on the left (passenger) side goes to the left hand side of the cylinder head, and is easy to see. This hose is tapered, the right angled end end fitting on to the cylinder head is quite large. I think it's 3/4" or even 7/8" at the end, quickly tapering down to 5/8" (I think. Standard heater hoses used to be 1/2" (ID) but Saab used larger hoses to get more flow through the heater and hence more heat out). The hose on the right goes to somewhere near the thermostat housing below the throttle body and is not tapered, as far as I can see.
So I'm guessing that it's the left hand hose that has split, at the right angled end. This is because it's the hottest part and it suffers from the engine movement as you open and close the throttle. If this is the case, I'm not sure where you would get a correctly sized hose with the bend in it, other than buying a replacement hose and then cutting it in the straight section and joining it, but is that worth it to save the effort of replacing it fully.
If you don't want to do that, contact Spectrum Hose in High Wycombe, Unit 5, Desborough Industrial Park, Desborough Park Rd, High Wycombe, Buckinghamshire HP12 3BG, United Kingdom +44 1494 524332, as they stock all sort of sizes as well as plastic joining pieces etc.
Contact me at the usual e-mail address if you need more.
Mark