Alright, I have a 72 240z with the stock engine and stock 4 speed in it. I recently noticed that when I let off the gas in any gear, I hear a clank noise, loud, not the small rear end thud from bad mounts (I have that too). But I'm almost sure its comming from the tranny. When I'm stoped, and let the clutch out into 1st gear, I hear the same noise. It sounds like metal on metal noise if I had to judge. Also, when I slip the trans into nuteral while I'm still rolling, I noticed vibration in the shifter that is consistant with rear wheel spin. I'm guessing off the top of my head that the output side of my trans is going out? If so, can I drop a 5 spd from a later model year datsun into it? Anyone know where I can find one, cheaply. I'm building a 383 V8 for it, so I only need something to last me around 3-4 months until my new engine is done. Thanks

Have you checked the u-joints in your drive shaft? If they are going out or have been damaged you may have some of the same symptoms.

I agree, sounds like U joints.

If you have been doing a lot of hard shifting, you could also have a bent shift fork or shift fork roll pin. Easy enough to do, not quite simple to fix, although it would be cheaper than trying to find another trans.

Besides u-joints it could also possibly be the front diff mount.

I vote Ujoint.Easy test.Jack up the rear end.Move a tire at a time back and forth by hand .Try it with the car in gear and not if needed.A bad Ujoint will allow too much wiggle room and slap.You'll see it or hear it. Have fun!! Daniel

Well, I tried doing that today, and the U-Joints are solid as can be...However, I can't say the same for my driveshaft...The forward u-joint in the drive shaft is my problem. Theres nothing left of it, and the drive shaft is about to snap in half. Junk yard has nothing in stock, but found one that can get here by Tuesday this week. So I think I'm going to order it if the other yard still has it in stock, waiting for a call to make sure and install it. Just wondering, they don't make a u-joint kit or anything for that do they? I pretty much have to buy the entire assembly correct? The yard wants $75 for the one they have, so I think I'll probally buy it. Thanks for the help in noticing it!

If it's just the u-joint that is bad, just take it to a local drive-shaft place and they can replace the u-joints. Probably for less than $40.

If your drive shaft itself is breaking apart (the tube body is coming apart) then you are doing some serious damage to your car!

I've seen lots of u-joints fail, but I've never seen an actual drive-shaft come apart, even in a research facility where that was the goal.

If the U-joint has gotten to the point the cups are gone and it is eating into the yoke on the driveshaft, you are probably just as well of to get another driveshaft from the boneyard. It would probably cost you as much or more to get the correct yoke and have it welded onto the driveshaft.

It could have been a lot worse, it could have been an input shaft bearing on the diff. or the ring and pinion.

I would suggest having the U joint replaced.Buying a junk yard part is just a band aid.It has most likely already seen its better days.As cheap as a new Ujoint is do it right and get it over with.I know your working toward big changes for you car but,it always seems those thing take a little longer than one thinks.I have plenty of friends that are in the 10th year of a house that was only going to be a temporary thing.The same with fixing up old cars. Have fun!! Daniel

Glad you guys told me that. I called NAPA and they said 8.50 per joint, plus the actual cost of the joint which is $17.50 each. So I'm on my way home to take the drive shaft out and they said they could have it done today, so thanks for the help!

Alright, took the car home and pulled it out, which I thought to be way to easy, so I figure there will be more problems down the road since takeing the shaft out was too simple. But I got it down to NAPA and they said they would have it down before 5 tonight, so I'm happy. Yokes didn't look damaged too much, a few fresh scrapes, but nothing looks bent or seriously damaged, I'll you know how it turns out and if it solves my problems. Thanks!

Sean,Glad it helped.I would have expected your last post to end with"tranny oil poured everwhere when I pulled the shaft from the tranny".Make sure you check the level.The square plug that sticks out behind the reverse swtch on the tranny.With the car level 90wt gear oil should run out when the tranny is full and the plug removed.That is also the location you fill it.I have used a heater hose and filled it from near the battery

Yeah, got it back on there and all is solved, car sounds great now. Well, except for my rear end mount thats clunking all the time, but that will get fixed soon enough. I jacked the rear end up pretty high, so tranny fluid wouldn't run out, so that wasn't a problem. I'v already had my nasty experiences with that stuff on my friends 280z. I just changed the fluid about a week ago, thinking perhaps it was low and that was causing my shifting noises, found out it was pretty low, but I drained it all and refilled it with new synthetic 80-90 gear oil. Thanks for all the help!