I am about ready to convert my 71 d-100 over to electronic ignition.
I have a distributor from my old 73 duster.
I also found a 76 valiant in the wrecking yard today with electronic distributor.
My question is there any differences in the advance curves?
And if so which years would be the best for a stock 1bl, 3-speed manual with 3.91 gears.
Thanks.

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1971 D100 SWB Step side, 225, 3 on the tree, 3.91 gear

After 30+ years, who knows what distributor curve is in any distributor you find.
You need to check the advance curve on a machine or take the distributor apart to see what you have.
As for what wil work best, a custom advance curve set for your combination and driving habits is "best".

Your manual shift, low rear gear combo will like a pretty fast advance rate and about 30 degrees total.
How heavy is the vehicle?
DD

I would estimate the weight close to 3500# it is a 71 truck.

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1971 D100 SWB Step side, 225, 3 on the tree, 3.91 gear

I would suggest keeping fairly heavy springs in the distributor. The heavier vehicles induce detonation with too much advance down low. The ligher A bodies like a little more low rpm advance, but your truck probably won't.

Mike

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Recognized by US Federal Courts as a Fuel Economy Expert!

I did kinda what Mike suggested. I used an 11.5(?) governer with a fairly light spring and a heavy spring from some slant and big block V8 distributers I had laying around. I have some snap off the line but instead of having all advance at a certain rpm, it builds if you will to where I spend most of my time driving (60-70+mph). Timing is set to 8BTDC, total advance is 32 degrees. Vacuum advance can is adjusted to come on at fairly high vacuum so not to over advance. Took a long time to get it dialed in right, but when you do its set and forget.

Go ahead and by a dial back timing light if you already haven't. You will need one to check advance curves.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2