Clunking / Shuddering with Locked hubs, 4wd not engaged

[HollyKate]

I have a 95 Toyota Hilux Petrol, Single Cab trayback ute

When I Locked the hubs, engage the 4wd, everything seems fine. Then, when I slow down, put the 4wd gear stick back to 2wd, but DONT change the hubs back into Free, it makes shuddering noises, like some one is banging on the bottom of the cabin faster and faster, when I slow down or downshift through the gears.

There is also a squealy noise coming from one of the shafts.

When I bought the car a year ago, I had an inspection done and they said there was some "Play at front uni joint/front shaft" and also "damp at transfer case - monitor" (I imagine this means oil leaks). I had the uni joint replaced, by the car dealership - now I'm wondering whether they actually did it.

Has anyone else had these kind of probs or does any one know how much it will cost, and what might be involved to investigate or fix this problem?

How can I check to see if the uni joint HAS been replaced? What does it mean by "play at front shaft" etc?

Thanks for your time. Appreciate a response from anyone who has ANY idea!!

[Mr DJ]

Hope you don't do this often , the front locking hubs are there for a reason, to engage or disengage the wheel from the front drive as required.
Use them unless of course you like replacing parts sooner.

With transfer in 2wd and the hubs still locked, you are using the wheels to turn the CV's, axle's, diff centre, front drive shaft & gear in transfer case. It's possible a CV or front uni is worn/broken and making the sound.

Just a guess from your post, you may need to replace both uni's in the front drive shaft.
If you can't tell if a new part has been fitted, might want to take it to a garage.