Help Whole Car Shaking!!!

[muscletruck]

hey guys and gals... i need your help bad... but heres the catch... its...for an old nova..not a truck...dont hate me..its a sweet ride... but heres the thing... we swap his th350 out with a 200r4... easy swap didnt have to change the drive shaft or anything..just the cross member and torque converter.... but anywho...we get the tranny in.... and starter her up to take her for a spin.... he drive around the neighborhood...everythign s fine...get on the open road... above 35-40...EEEK.....the entore car shakes.... then when we slow down......shakes hard then goes away.... so check under the car... the drive shaft out of wack... the back u joint not centered right... fix it... then it still does the same thing... did we mess somethign up???....help please!!!

[Palf70Step]

My guess is a something with the U-joints. I'd also double check the length. It's probably Ok and just a bad joint, but maybe there was just enoughdifference in the length of the two tranny's to through the driveshaft angle off just a hair.

Since you mentioned it, if you don't find something with the u-joints, I would then suspect something with your Torque convertor. Maybe a bolt came loos or youir flex plate cracked