My old YL is a 37 series #3755301 and the shaft diameter is .467
I used Crane steel gear #34970-1 (Not available any longer?)

Greg,
I might have been interested in your offer before I purchased the new Unilite- it's way more then I need. I do see in your picture that you circled the C and F springs which are the ones that I figured that I wanted to try, had I been able to score the springs. They are the Green and Gold springs.

If Cleandan has the Green and Gold springs I would be interested in your spring kit. I'm in SW Montana.
I keep my old YL #3755301 in a box in the back- just in case? Seems many people have had problems.
I have never had a problem with my Unilite which I guess is about 40 or more years old. I just never had the advance spring kit and now I want my total advance in earlier.
The new Unilite is working great- so far, but I just thought that it wasn't as solid as the old distributor.
I have the key. I would still like to have the springs.
Jim

Mike, thanks for the info.
I have looked all over the internet for Mallory advance springs for any engine make- nothing found.
I know it's a long shot and may never find any. I have used this original 3755301 for probably 40 years with no problems and I have the advance key but never thought about changing the advance curve. In fact I bought the new version and installed it on my 427. The new one is a great looking distributor; billet and polished but I don't think it's as good as my old one. The new one is nice and tight on the top side but actually has some slop in the shaft at the bottom. I put a steel gear on it and installed it, also changed the advance springs, I'll continue using my old MSD-7AL and my Mallory CD transformer. I haven't run it yet.
Jim