shaking motorhome

upon picking up speed from standing start , i find my van shakes a tad , this is the second van out of the 5 i have had that has done this , the first a swift kontiki 2.5 td this one an autotrail scout 2.8 jtd . the kontiki i had the drive shafts replaced but still did it engine mounts ect all ok . i have done nothing with the scout as i beleive it only to be the touque at low speed as when at speed the shake stops . 04 plate vehicle , have any of you had this problem ???