Well I have been having the bucking/vibrating problem everytime my car shifts into third gear (about 45-48 mph). Tranny downshifts fine. Fluid has never been changed 114,000 on it, I blame my dad for that one.(its not bad though, just a little dark). Anyway, I was reading in the manual for the 4L65E(and I know thats not my tranny, but its the only tranny book I have), that among other things, the ignition coils control tcc lockup.So I checked the resistance in all coils. BTW my dad replaced the 2/5 coil before.
Results: 2/5 Primary = .4 ohms ------------Secondary= 8.35 K Ohms (this is aftermarket one)

1/4 Primary = .5 ohms------------Secondary= 5.82 K

3/6 Primary = .5 ohms------------Secondary=5.75 k

Now; is the aftermarket coil not matching the origional coils' secondary resistances gonna hurt anything? Could It cause my TCC shudder. Is it worth it to change the other two origional coils to something matching the 8.35 kilo-ohms of the 2/5 coil? The car idles fine and steady. Thanks in advance

Pull all 6 plugs and see if they all look identical. Light tan color. If they do, leave the coils alone.

Only replace a coil for a two-cylinder misfire.

Will do. Thanks willwren