I am looking at buying a 94 40 foot grand villa,it has a detriot 350 with a allsion 4 speed.My friends tell me a 4 speed will get bad gas milage,and run in the high rpm,they say to get the cat with the 6 speed,any thought are needed asap.can a 6 speed repace the 4 speed on the Detroit
Thanks

Well it is with out say normally you get better fuel economy with a higher geared unit however that grand villa with the 350 detroit is a great coach and from what I've seen they get pretty average fuel economy. Remember if you drive 55 verses 65 you get better mileage too. There are alot of New coaches out today that only get 5-6 miles per gallon so I think you will be happy with the grand villa. Is it a private sale? ask owner what they averaged. Good luck Ron