83 k10 blazer busting u-joint like crazy

[69chevytrucker]

got a stock height 83 full size blazer i put a 350 in it and now i cant drive it because as soon as i start going alittle fast it shakes and then blows out a rear drive shaft u-joint first was rear axle then i put new rear and front u joints then next run blew slip yoke side u joint now my shaft is garbage and i need a new one but why are they breaking and yes they are put in right,

[68Timber]

Had you ever driven it before putting the 350 in? Are the yokes in phase? I would put the rear on jack stands and turn the drive line and look for run-out.

[69chevytrucker]

Originally Posted by 68Timber

Had you ever driven it before putting the 350 in? Are the yokes in phase? I would put the rear on jack stands and turn the drive line and look for run-out.

ya i drove it when it had the 305 in it.
i think i figured it out looks like i got a u-joint for the axle side and it has nice thick snap rings and the joint i put on the slip yoke side ended up having thin skinny snap rings and it looks like one must have popped out making me lose a cup and the shaft fell off. going to get new joints and a new slip yoke now that its trash and build another .

[69chevytrucker]

another case of napa selling one good one and one cheap one lol supposed to be the same joints