Quote: What converter is in it now? the stock one or your good one? What about running it with the converter unbolted, are you absolutely sure there is no engine vibration. I thought the B&M plate with the section missing was for a 360 with weight on the converter but You had a balanced converter did you not?
There is no way to start the car if the flexplate is unhooked... the starter spins the converter, not the flexplate, unfortunately we arent chevy boys in this aspect...
On page 3 you said you tested the car with the driveline removed and it was smooth as glass, and that it had to be behind that, so why did you rip the trans out of the car to try this other one?
Also, you asked about the measurement side to side of the driveline in the car, and the motor, trans, and drivelines in our cars are all offset about 1 3/4 inch, for the steering column and gear, thats how they came factory, so I dont think thats an issue...
Heres how I diagnose it...
If its REALLY only in 3rd gear, and it changed RPM/speed with all 3 chunk swaps, then its a drivetrain RPM issue, and not an engine RPM issue, so it CANNOT be motor, flexplate, converter, front pump, or input shaft related... its gotta be in the back of the trans rearward...
If it REALLY went away without the driveline in the car, that proves all of that as well, unfortunately it doesnt really rule out the back of the trans, because if the output bushing were worn, then maybe the weight and force of the driveline is straining the trans causing the issue, but since youve had several trannys in the car, i dont think thats the issue..
You probably didnt get MULTIPLE bad drivelines, and u-joints, and you have tested the car without the wheels and brakes, and tried different gear sets with no difference either, so your really running out of possible options here..
SOOOOO pretty much the only thing left is:
Rear end could be installed crooked or bent, maybe the spring mounts, or the whole housing is tweaked or something, causing the u joint to bind, and causing the vibration. your car leave pretty hard, so its probably taken a beating, maybe you should backbrace the next one. Are the U-bolts tight? Those are the only things I think would follow the logic of everything you have said, and explain the issue.
Dont know what else to say man, there is alot of conflicting issues in the thread, and it gets hard to comprehend it all... I think your on the right track trying the rear end next, but if that doesnt fix it, i say just beat on it until something breaks, these old mopars are weird sometimes, it could go on for years lol
Good luck.
11.48 @ 120 with a 1.80 60' 318, stock 1.88 heads, stock 904, Pump Gas, 13 lbs of boost.
9.94 @ 134, 318 on pump gas, 14 lbs w/ Eddies, transbrake 727, 3600 lbs, 3.54 gear and 28's.
