Hi, I have a 1985 300TD with some big concerns.

So I was taking the NJ Turnpike from Mullica Hill (South Jersey near Philly) to Staten Island and as soon as I got off the turnpike, I started hearing this 'thwopping' noise coming from the rear passenger wheel area, and as I get slower (< 15mph) it turns into a clunking noise, and at times with a noticeable clunking vibration thru the body of the vehicle. Almost like it's got a square wheel or the lugs are loose or something.

It's come and gone and is NOT consistent, but I've only driven it for about 4 days now. I did a 120 mile trip (each way) to/from Staten Island to South Jersey, TWICE (friday and today), and then a 45 mile trip (each way) to work on Monday. It only seems to be noticeable immediately after driving it fast (>75mph) and for over an hour or two. I can't say things conclusively because I experienced it today and so I don't know how it'll fare tomorrow. When it started on Friday, I got off the turnpike and noticed it at the toll booths. So I stopped, parked, turned the vehicle off, freaked out, and since i didn't see anything, I drove off. And it was totally gone. And today with the same long drive, I decided to keep on going instead of stopping and the noise/vibration persisted. It's almost like for some reason putting it in park somehow fixed/reset it, though I can't confirm (I haven't tested).

It really sounds like a clunking/thwopping like it's some gear assembly with a loose or broken gear trying to turn.

I don't see anything obvious in the back. I took the passenger rear wheel off to get a better look, nothing seems loose. The bolt that attaches the driveaxle to the rear arm looks totally tight. But my GUT says there's something of issue with the driveaxle. It really sounds like the gearing is damaged or loose.

I also did some brake work, replacing the rubber hose, cleaning the caliper, etc.. I noticed about a month ago that the hose was loose and that's why my brakes gave out within a week. I fixed that, but noticed the caliper was actually put on with the hose twisted - so really I think eventually it needs to be turned one rotation. I'm wondering if maybe the brake caliper is acting up.

I will say that I notice this clunking especially when I am pressing ON the gas. When I let up, the noise/vibration mostly goes away. So I'm kinda thinking it could be transaxle/drivetrain related (though it seems specific to the passenger side).

Can anyone confirm this is a possibility (likely or unlikely) or if there are other obvious possibilities?

Besides this, the vacuum system has decided to go haywire - there is a bunch of fluid stuck in the tubes and so the ignition wouldn't cut off. For now I am using a mityvac directly connected to the cut-off and manually pumping it when I pull my keys out.

It feels like the car wants to break down. Or break up. Either way I kinda feel like I want to cut my losses and just junk the thing (eventually). I may just keep it for round-town type of stuff. Until I notice things getting worse or consistently bad. I actually commute 90 miles round trip each day and so I don't want that stress.

I've actually already done a lot of work to just get it running safely.... The steering was unstable, the brakes gave out randomly, and the shifting flares between 3rd and 4th (I ease up on the pedal right before shifting so as to avoid the flaring).

I got the car for $500 a lil over a year ago, and from a guy who had it sit around who got it from a guy who had it sit around, etc... and it kinda goes back to what seems to be owned by a church pastor. There was a parking placard in the glove box. It's pretty clear that most of the work over the years was hacked instead of done right, probably because the guy didn't have a lot of money or because he didn't directly pay for it (the church did).

I'm honestly at a point where I have zero desire to even attack this project. I have a 300SD sitting around in the middle of a repair (leaking crankshaft seal, but the pulley bolts got stripped so I was stuck until today when I pulled the bumper off and used a strong drill with cobalt bits and a screw extractor) and also a Ford school bus I've been converting to a motorhome. I'm thinking I'd rather finish the 300SD car tomorrow morning if I can and if not take the chance with the wagon until the weekend. I've learned that I am CAPABLE of auto repair, but I'm at a point where I'd really prefer to not NEED to constantly fix something that is breaking after 25-30 years. I got enough stuff to worry about that I feel like I ought to just ditch all my cars and live in the motorhome and drive that around and when I can't find a place to park it (ie in the city), to either take public transportation or use my bike.