Hi guys, I'm brand new to the forum but not new to building conversion motorhomes or mechanics in general....my passion is building race cars from the design page on up. I have a 1980 GMC 6 window (34 passenger). It was given to me about 8 years ago with a blown up 366" from a church that didn't want to put any more money into it after they blew up the engine. I ended up putting a 454" pick up engine into it with a fresh 400 series Turbo tranny with a shift kit and an RV converter. At present it has the stock intake, an Edelbrock 650 carb (yuck) and the stock large volume 366" cast iron exhaust manifolds with a single exhaust and a Turbo muffler and the full length bus tailpipe. I have an Offenhauser Dual port intake for it with an 850 CFM Quadrajet carb and a set of headers and I'll run dual pipes out the back with Turbo style mufflers when it's all done. The conversion from the tall deck 366" to the shorter deck 454" wasn't an easy one because I decided to reuse the bus 3 core radiator, the 366" water pump, big alternator and the body specific power steering pump, basically all the external accessories that came with the body. They all bolted to the block just fine with the exception of the larger 454" harmonic balancer (which was 10 1/4" in diameter because the 454" is externally balanced). What I ended up doing was turning the OD or the outer balancer ring down to the required 10" to clear the 366" water pump and in the process I turned the face back .100" and left a register ring in the center to fit the 366" crank pulley. I moved the accessory bracket mounting points out 1/4" to line the pulleys up with the crank pulley and viola! a great running 454" late model pick up engine with the big truck style water pump, alternator and power steering pump attached. Oh, and I blocked off the transfer hole that used to go into the dual thermostat housing that was used on the 366" with a brass freeze plug and some JB weld to epoxy it in place and made up a new bypass line by tapping the 454" intake and using one of the heater hose holes on the pump and made up a -6 braided stainless steel line....done deal. The body had a granny gear 4 speed in it with the bell housing style rear motor mounts, I removed those brackets from the chassis and used a Chevy van rear cross member to mount the tranny, shortened the stock front driveline, installed a yoke that would accept the right u-joint for the 400 series yoke and it was a done deal. If you all would like to know anything else, feel free to ask.