Why wont it fire?

[don t. - 72gmc]

Yesterday was my grand daughters b-day and I just hadda drive the 70 GMC for the 1st time this year. Checked fluids, all looked good. She fired right up. Drove around for 15 miles or so. Tranny was a little low, topped it off. All looked good, off went me and the wife. About 50 miles later, at a stop light, the truck started bucking abit. Threw it into neutral to keep her running. Never did die. Had to make 1 stop on the way, fired right up, things didn't change. Made it to the party. Went to leave was the same. My SIL said stop by and we'll fix er up.

Cleaned up the points, made it worse. It fired but was bucking worse than b/4. Cleaned points again, back to original condition. Went to the local AutoZone, which was a joke. Besides not having a clue, parts were not in stock. They did give me directions to NAPA. I bought a dizzy cap, points, rotor, condensor and a ballast resister. Replaced all but the ballast resister. Truck cranks real well but does not fire. Pulled cap, rotor does spin. Pulled coil wire to dizzy and grounded to block. Little or no spark. At this point, I didn't have a multimeter to check volts. SIL handed me his keys and said see ya tomorrow.

While lookin around I noticed....
....black wire into dizzy has a flat spot, kinda like it got caught under the cap. It doesn't look cut but???
....There is a condensor on one of the coil posts. This is inaddition to the condensor under the dizzy. What's this for? Don't remember ever seeing one there b/4. Sorry, don't remember which post.
....Is there a ballast resistor? I am unable to locate something that looks like what I bought. My other truck is a 72 GMC 2500, but its HEI and aint got these parts.

Things you'll prolly need to know....problem truck is a 70 GMC 2500 400BB w/a 4-bbl q-jet. Auto trans w/factory ac. Coil is stamped as 12v, use w/external resistor. 93,000 miles on original engine. Truck appears to be original, no mods that I can tell. I did show it off to y-all about 4-6 weeks ago. I would have attached a link, but Im at home currently connected at 19.2K, and its taken me about 30 minutes to get this far. The dog needs to go out. I'll try and find my prior post and reply back.

FWIW....4 of the 5 parts I bought from NAPA had "Made in the USA" on a sticky label on the box. All were Echlin.

Thanks inadvance for your time.
I do appreciate it.
Have fun.....don t. .....