My 2.5 2003 sorento went in for an mot on Monday, it drove perfect but when I picked it up and drove over 35 then let off the accelerator the car woukd make a huge knocking sound. The sound seemed like it was something to do with the drive shaft/gear box/transfer box. I thought he had put it in a single axcel rolling road but after asking him at the mot center he confirmed the jeep had not been on the rolling road. I took it to a freind who is not a machanic but he's always building jeeps and swapping engines and so he knows what he needs to. He had a look under and said the drive share seemed a little rattley going to the rear, he topped up the gear pik in the transfer box and now it seems a little better, I can get to 60-£70 before it starts knocking, it actually feels like the engine is going to drop out. Any help please