wining diff and noisy radiator fan...
 

hi im new to the site and was wondering if anyone can give me any advice on a couple of problems i am having with my car.firstly the diff is wining alot and has been doing for a couple of years now and is gradually getting worse, it tends to wine on accleration until i hit 70mph then it goes quite,i have taken it to a garage who have said it will be over a thousand pounds or alternativly i could get a second hand one or turn my stereo up...i have an s class 320 but wouldnt know where to start looking for a second hand one or who to trust buying one from, any ideas...?
secondly, about 8months ago it was converted to lpg and since then the radiator gets very warm and the temp gauge gets just past half way which makes the fan run constantly,any ideas on how to cool the engine...ie bigger radiator etc..

any help and advice would be greatly appreciated,

thankyou,

sarah