A little light reading indicates that Volvo started using the flywheel position sensor on the first OHC engines in '76. It is there to provide a more exact method of setting the ignition timing. But in order to do that you need the Volvo mono-tester #999-9921 (according to Haynes). And we all know everyone has one of those lying around in the workshop, right? I may have made it sound like the flywheel position is critical to proper operation of the ignition but it's not so I hope I didn't mislead. The other end of the sensor is simply a connection for the instrument.
So, as Robert indicates, flywheel position isn't really important on the early cars unless you are using that device to set the timing. Later cars? I don't know. I've not owned anything newer than an '84.
I would still strive to position the flywheel correctly but I'm a little bit nuts that way.
--
'80 DL 2 dr

ahh, I get it, thanks...by the way, I read the section in the haynes manual and all the posts here about accessing the top transmission bolts by pivoting the rear of the engine down and using extensions from below (and dutifully went out and bought the long extension I thought I'd need), but I found the easiest way to be from the top, inside the engine bay, with a box wrench. Rotating the starter hole on the bellhousing around the tunnel hump might have been easier the other way, but it wasn't bad. Putting it all back together might be another story, though. As it turned out, the hardest part was accessing the allen bolt on the shifter, which took about the same amount of time as removing all the bellhousing bolts and dropping the whole transmission. Anyway, thanks again for the help.