Just to add, I also own a VW T25 Camper (Tin-Top stylee

). Mine has the 1.9 flat four petrol motor, but some have a 1.6 Diesel (either turbo, or non turbo) and it is pretty common on those to do it the other way around, ie Diesel out and Rocco (Passat/Golf/Audi) motor in. Some folks go the whole hog and take a 1.6na out and put the 2Ltr TDi Diesel in and apparently they go very well for a heavy camper van.