Or use a 90 to 60 reducer for each one and an equal 90mm y piece. Could be fabbed up in steel cheaply but one of these might do http://www.ebay.ie/itm/90-90-90MM-Y...DIESEL-NIGHT-BOAT-CAMPER-HEATER-/111810641881
Id go with whatever fitted neatest and best fitted the space Im a fair way off that stage yet but will need to get somthing sorted quickly once the van is on the road Hopefully someone else will have put the time and effort in by then and i can just copy them
I sent the fiberglass y piece up to @Paul Weeding Hes going to use it to make a mold He reckons he can make one out of a different type of fiberglass that will make it flexible enough to fit No offence to paul but i cant see it myself but id be very happy to be proved wrong I think the best idea would be to make the y piece out of silicone so it was squishy to a degree so it could be squeezed over the rear beam It then could have stainless inserts in the end to give somthing for the hose clamps to squeeze against It would look like the original and would never rot out
More good tips as ever. I have just removed the y piece and surprising rust free ( unlike rest of van). Thinking of painting it up white - keep the heat in the piece as black paint would surely reflect the heat outwards? Anyone know of a good plastic substitute for the main heating pipe back to cab?