Somewhere I read that you can get a collar to put on the distributor shaft to make the timing more stable. Anyone have pictures or any info?

I believe he is talking about a additional collar the goes on the lower part of the shaft to reduce timing jump. It is held in place by some set screws.
http://www.hughesengines.com/Index/produ...mp;partid=25200

how does that work?
or rather what is it preventing from moving?

This is what you want.
http://s542.photobucket.com/albums/gg408...pg&newest=1
at Hughes
http://www.hughesengines.com/Index/produ...mp;partid=25200
When the drive gear bounces up and down it turn a bit moving the timing back and forth this collar really works.
I made mine some get 1/2 motor shaft collars at TSC (tractor supply)
I used a 1/2 locking nut drilled out and tapped for a set screw. But dam it really works
http://s542.photobucket.com/albums/gg408...pg%26newest%3D1

What will do the most to achieve your timing jump elimination is a timing chain tensioner kit.

When there is room for the oil bump/distributor drive gear to move up and down it naturally turns.
Like when your turning the gear in and out with a screw driver! and when it turns it affects the timing fore and back.
so the collar holds the drive gear down into place so it stablises the timing a lot. I have a milidon gear drive and still had a problem. the collar eliminated the problem completely!!

Try this
close the gap on your electronic distributor some--it makes that jump go away most of the time

interesting. Thanks for the explination.

(1) close the reluctor gap to .006" at the tightest point as different reluctor vanes stick out farther and the vac adv will pivot and change the gap also (got a Mityvac) (2) get the collar and slide it on & snug it w the setscrew and install the dist all the way tightened to the block w the clamp then carefully remove the dist and fully tighten up the collar in it's located position. (3)Get the aforementioned timing tensioner and a GOOD QUALITY tchain set. EDIT also 1st remove the oe roll pin/collar that's in the oe location in Drjayo's pic and add shims to reduce the shaft end play to near zero & reinstall it. The added one is seperate and goes on the end just above the tang