Engage the E brake and get under the truck between the front and rear tires so you can see the ujoint on the drive shaft that is connected to the yoke going into the tranny. While you lay still, have your girlfriend or wife release the E brake , let it roll atleast 6 feet and see if there is any play in the joint !

JK Don't really do that, the best way is to lay under the front tire.

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98 1500 4X4 5.2,SC3815, HS 1.7's,Borgeson shaft,
Fastman TB, Hughes Plate, 4x4 Posi-lok
Magnaflow Cat. w/Flowmaster 50 series, Rock Solid Ram Steering fix