My 1992 RRC 3.9efi V8 SE Vogue was converted to run on lpg in 2000 with 63000 miles on the clock , by the second owner. He used it for towing a large twin wheeler caravan throughout the u.k. and europe. He px'ed it in 2008 , with 168,000 miles on the clock , then I took over its keep , and have towed a trailer tent and then a 16 ft. caravan for the past 18 months. It now has 180000 miles on the clock. It is still the original auto box , and apart from a cam shaft change a couple of years ago , and a cylinder head gasket this year, the engine is untouched ! What I can tell you though is that the oil and filter has been renewed every six months for the past 17 years , and it has a full service history which include regular auto box oil changes and axle oil and transfer box oil changes.The lpg system is italian (lovetto)and as far as I am aware has only had the stepper motor renewed in ten years , and two replacement torpedo tanks , as they only have a ten year serviceable life. The V8 is joy to tow with . I use the box manually sometimes to aid standing start acceleration , and switch back onto petrol on some steep hills as you get a little bit more "umph" ! So the moral is, get a well cared for vehicle , whichever you choose , but with LPG currently 54pence a litre in my locality , the v8/lpg engine has to be worth a look .