Have you looked at the actual Bluebird wanderlodgesa that came from the factory as a coach. In 77 they had a Forward Control (eng in Front) Cat 3208 with an allison 4 speed auto in a 31-33- and 35 ft models. A good site to check out is www.vintagebirds.com it will give you history and specs, there is also a for sale section. Another good site is birdconnection.com You can find wanderlodges ranging from the low 20's up in 1980 Bluebird went to full air ride 1983 the 3208 got a turb and hp was bump from 210 on the NA models to 250. The pre 80 models did not have a driveline retarder. Check out the wandelodge groups on yahoo.