I used to do my own maintenance but have grown older so hired a good man for the job.
Here it is: I have a vibration that is getting worse (feels like I'm driving on rumble strips).
1978 Ford F 150 4x4 Dana front an rear 3.55's semi slip 4 speed standard 351 M.
I've rebuilt the engine 12thousand miles ago, had drive shaft ujoints rebuilt, new yoke on rear pig, changed all fluids in drive line. did put in heavier rear springs, replaced the hangers and shock mounting hangers. All that before we moved south. Could the degree be off at rear pig. i set up like stock spring(in Ford manual, I think 5*)
When we moved from Ohio to Arkansas(2007) the truck didn't have this vibration it has today and my mechanic has know idea what would cause this. The vibration isn't as bad under load and at 55 it's pretty quite.

And i hope i have this listed in the right place. i ordered this from Cole Motors in Ada,Ohio and they just closed last year.
Thank you,Jerry I don't know what tags are