Be carefull on motorhome intake swaps. If it's a '72 and older class A with a 318-3 engine, they use a water crossover under the carb.....not exhaust. They don't interchange. If it's a 318-1 (like cars and pickups) you can bolt on a '66-7 273 intake if you're going to use a square bore carb, or, a '78-up 318 intake if you're using a spreadbore. I know, you can use an adaptor, but, that always seemed Mickey Mouse to me. Keep in mind, that the later intake has EGR and other smog features that you may want to sterilize. If it was me....I'd put on an aftermarket intake that's matched to the internal engine specs and carb I'm going to use. If you have the 318-3...you're screwed.