Earthquake in truck.... Could be this or that, need advice
Ok PSN here we go with another dilemma. So last night I'm heading to church and on the highway traveling 70. All is going smoothly no concerns then suddenly I feel a slight bouncy feeling, and noticed the bed of the truck rattling like it's having a seizure. Take foot of accelerator and vibration continues, no noticable sounds or other of feelings. I slow to a stop, I see nothing obvious underneath ( granted I want crawling under the truck in my suit). While stored truck was idling normally and no new smells, or obvious fluid leakage front or back.
Get back in truck and take off normally, all starts off well, get up to about 50 and the truck feels like the back is bouncing, guess it looked the music on radio (lol). It's a manual transmission and I also noticed the shifter shaking way more than normal when accelerating, the shaking slows when I let go of the pedal but it's still shaking around real good. Can't get over 50 for great if bouncing off the road. Put on hazards and limped the rest of the way 40mph still feeling bouncy but able to drive and maintain Lane. No pulling to either side either. After exiting highway, had a small trip about 7 blocks to destination and truck was fine, no trouble shifting, no noticable bounce, nothing. However I never went over 30 (city streets) breaking felt normal to, no sounds or dragging sensation or smells.
After service in called into work and decided to limp home at 40mph, as I started through the city streets I could feel the bounce start again, even at low speed now, get on highway and start my hour long journey, only able to get up to 45mph to stay safe, bouncy feeling gets crazy worse if I go any faster. As I'm driving I still feel/see the bed bouncing/shaking, I also hear that the bounce/shaking increases when I accelerate, if I took my foot of pedal the bounce/shake decreases. This was discovered because I have a pair of leg restraints on my duty bag in the rear bench, I can hear the chain constantly while driving and increases in does as I accelerate.
Had my wife drive along side me (took two vehicles because I usually leave for work right after church) she said the truck looks like it dancing in the back shaking it's booty.
Made it home and there is a large Hill before my house downhill slope, took it out of gear and rode the hill down, all felt smooth no vibration or shake. Once home reverse felt fine and parked it. Going to crawl under it when I get home in a few hours but not really sure what to look for.
I'm thinking carrier bearing going out or is dead? But no sounds that I can hear (Granted the truck is loud already though).
Maybe the drive shaft lost balance? (Is that a common thing eyeballs all of a sudden)
Can u joints do this to?
Ideas and input needed and appreciated.
All stock, no mods, haven't pulled anything since I've had her for the past few months.
Last thought I thought maybe tires but would that cause the shifter to shake around like I was running over rumble strips that were 4" high?
Sorry for the long post, just wanted to give as much info as possible to get some good feedback