I'll 4th the mount.

I have a lot of faith in the GM transmissions, you might be as happy as me, when you find out it'* just movement under the hood and not your tranny taking itself to the dumpster.

Now.. I don't want to jump ahead of this.... but.... if this is engine movement, you can either make your own engine (transmission mount) for roughly $15.00 out of 3 hockey pucks and a bolt, and lock washers, or you can buy the $60 - $80 stock mount.

If it is your mount causing the clunk, I would skip the factory replacement & just go for a solid as suggested. I replaced mine right after buying my Bonnie & it didnt last a year before it came apart as well. So I chopped it up for the thread ends & welded a piece of 1" heavy wall pipe between them & put it back together.
The only thing I don't like so much is it dose vibrate a bit through the car now, I would think that the hokey puck method would dampen that out though.

Not very well. I had a hockey puck mount on for 15 minutes and took it off because I don't want the vibration. I'll happily replace my mount every year to have the smoothness. Others have had issues with vibration, but most seem to tolerate it.

Hi , i made the first solid mount for the 2000+ Bonneville. Have over 140,000 miles on it with NO complaints.
Go outside, lift the hood, rock the car(back and forth) in park, see all that movement
that is not good for all the fule lines, electrical lines, exhaust pipe so on and so on.
When you have a solid mount it wont move a lot, it will still move just not a lot.
It will also help the torque steer and it will help put the power to the ground. I would
make the new mount out of wafer'*(3" round) from the sidewall of a tire. I have made
two like this and if i didn't already have one this is the one i would make for my car.

ROD

The issue I have with promoting the solid mount is that you don't give the WHOLE story. It didn't make sense to me that GM would make an elaborate dampening mount if it could be replaced with three hockey pucks. But hey, there are all of these reports about how well it worked, so I made one.

NOBODY and I mean NOBODY said ANYTHING about extra vibration until AFTER I put my old stock mount back on and mentioned that it was BECAUSE of vibration.

Many seem to tolerate it. I don't. I also think it is misleading and should be mentioned when promoting the solid mount (I know I felt mislead). You know, FULL disclosure...

Hawk, do you realize you are the only one that has ever complained about the vibrations? Don't you think its a possiblity you had another problem? or maybe even made the mount a little different?

I know I'm not. Several others have said they have but they don't mind the vibration. But it was only AFTER I brought it up.

Here are others:

http://www.bonnevilleclub.com/forum/...ic.php?t=81798

Well i don't have the vibration you talk about, Yes i feel the car more but it'* not a vibration.
My drag car has steel motor mounts no rubber at all and yes that car vibrates.
On the Bonneville you have 3 stock(soft) mounts plus the front solid mount that you make,
but wait the solid mount mounts to the crossmember and that crossmember is mounted to the
body with "rubber mounts". So it(the engine) can still move(front to back) just not as much.
I know the height of the front mount makes a difference that is why i say measure your
stock mount and build the new one the same height. Heck i put wider tires on my car with
stiffer sidewalls and now i can feel the road better, but i don't say i feel a vibration so i'll
go put the crappy stock tires(235/55-17) back on.

ROD

Yes I have to agree with Rod.
I don't have any significant vibration at all.
I have had the mount for three years now and wouldn't ever consider going back to the original mount.

Hawk, you must be very sensitive.