Thanks Rgrinder.
I will give it a try on the weekend, and will let you know the outcome.

hey bro, I've seen this several times as a nissan tech,and it sure sounds like you have a bad rear u-joint.when you let off the throttle, this releases the torque on the drive line causing it to snap back.noises can be the most difficult to diagnose but I would start with the drive line.
hope this helps.

Thanks roughneck

From what I have read, the u-joints cant be replaced, so its a whole new drive shaft needed if thats the problem.

Can any aussies tell me a cheap way of replacing the drive shaft? Can they be reconditioned or something?

maybe you could try a wreaker they shouldn't be too dear and they are usually ok

I was going to visit the wreckers, but there isnt a lot around this area.

Will a drive shaft from something else suit a ute (eg 120Y,sunny etc), or are ute stronger/bigger?

What tranny do you have? If it is the standard 1200 four speed, then you're stuck. It has a smaller output shaft than every other Datsun tranny.
Oops, sorry just re-read your original post. With a five speed, you should be able to fit one from a car with serviceable joints. I've heard of people having joints installed in the non-serviceable driveshafts but have never attempted it myself.

I have a sunny tailsharft in mine and its a 5 speed with a c20 4.8 diff ,same as a ute but I had to change the yolk on the front of the diff to a sunny one as the c20 one was too long.I think the ute one you have maybe ok though. most of the tailsharfts seem to be the same length ,its the yolk on the diff thats different. anyway a sunny one got me out of trouble.i hope this helps
by allan

Are we absolutely certain the stock 1200 u-joints cannot be replaced? I seem to recall doing so ... maybe it's like those Chevrolet "non-serviceable" driveshafts. They could still be pushed out and replacements put in. They were supposedly locked in by some sort of plastic glue, but with a little extra pressure they still came out just like serviceable u-joints. All the parts stores carried the non-replaceable replacements.

Hi Dimlights,

I have a 5-speed with the small splines on the tailshaft and clutch shaft. I had to change driveshafts when I changed from the dogleg 5-speed a couple of months ago to a standard 5-speed. This tranny has the same clutch splines as the 1200 4-speed also. I don't know what it is out of. I picked it up out of the lot at my uncles scrap yard a bunch of years ago.

Mareo

Mareo, I guess that transmission is the exception that proves he rule.
As far as the non replaceable U-joints, tensandtwenties forced me to actually look at some driveshafts the other day. I have to concede that I may have been misled when I was told they were not replaceable. I'm going to have to stop quoting "common knowledge" and only relate what I've seen with my own little beady eyes.