Hey

Just today i've installed another R200 into my 76 as the last lost the holding pin and cacked itself, this new one has around 1/4 turn drive pinion slackness, and makes a loud noise when pressing the accelerator, is there any way to adjust the slackness or do i have to get another diff. And i am completly sure that it is this noise, as when i turn the shaft i hear the same noise

Well, it can be adjusted. It is not as easy on an R-200 as it is on the R-180 but it can be done.

However, if you have as much freeplay as you say, I doubt you will be able to adjust it out, sounds like the ring and pinion have far too much wear. You might want to pull the back cover just to see for sure, but if it really has a 1/4 turn of freeplay in the pinion, you are probably going to see a lot of wear on the ring or the pinion gear. :disappoin

If you find a lot of wear, you will probably be better off looking for a better diff.