Slip Yoke Problem

[Ceedawg]

It should not rock like that, maybe up and down, the splines on the mainshaft and correct yoke will not allow that much movement. Get a factory used yoke and never look back. Millions out there, very common from 70 up. By the way my 66 has 1330 u joints and the tone ring. On The factory yokes the cups do not sit out that far, maybe a 1/16”. Throw that Chinese crap away.

 

[HotRod777]

The wrap-up:
I went to a different drive line service with my drive shaft. He had a new slip yoke in stock that we tested mine and then his on a 727 that he had sitting on the rack. The both fit. He pressed on the new yoke and also balanced the shaft. He did say it was "out" almost 30 thousandths. He added weights and a tad of heat and got it within 10 thousandths. He said that on a cruise car (1500 mile a year at most) it will be fine. When I installed it the yoke must much snugger in the tail shaft bushing. The test drive yielded an honest 80% improvement which I can easily live with. Thanks for everyone's input and offers.

 

[R/T Boy 67]

One final note on the spline. I did some research and discovered that the OD automatics used a different spline than the standard 727. The yokes are identical otherwise. The yokes you purchased were probably for an A-518 OD unit.