Also check out the Classified section of WFM www.weekendfreedommachines.com if you haven't already done so. I see 318s popping up pretty regular there.
Also the 330, 332, 322 and the 316 Onan are in the same series as the 318, so those might be a possibility, especially the 332 and the 322 as they're basically a 318 with a different engine and includes all the 318 features.
Also the 330, 332, 322 and the 316 Onan are in the same series as the 318, so those might be a possibility, especially the 332 and the 322 as they're basically a 318 with a different engine and includes all the 318 features.