Slight vibration at the OD shift

[roadrunner88]

I get a slight vibration right at 48 MPH when the trans shifts into OD with minimum throttle (like you'd be holding 49 mph, say). Vibration feels as if it's the driveshaft or at the pumpkin.

If I let off the slight throttle and it mostly goes away.

Accelerate slightly and it disappears above 51-53 or so...

any ideas what's about to need replaced?

 

[441120]

Is it your torque converter locking at the same time? I had an old chip that at certain conditions would lock then unlock right when shifting into overdrive.
Maybe trans getting tired?

 

[roadrunner88]

Doesn't 'feel' as if it's locking.

Feels as if it's 'wobbly' right where the shaft enters the rear diff (if that's any kind of explanation) but only for the exact scenario described above...

My temp fix: accelerate smoothly through or stay below the OD shift till I can accelerate... a half measure to be sure....

 

[Squid4life]

Is everything tight at the u joints and pinion yoke?

 

[roadrunner88]

Is everything tight at the u joints and pinion yoke?

I'm checking that today... How much 'play' (if any) should there be in them?