Well Cadillac, Oldsmobile (and Buick) had front wheel drive 5.7 diesels engines (Eldorado et al). They could be mounted to the typical GM motor mounts. But power is something else. A Naturally aspirataed 6.2 is not really sufficient for a big motorhome, a 5.7 would be severly defficient, call that slow!!
83 C10 Suburban, Silverado, 6.2, 700R4, 3.73, 31-10.50R15
82 C30 Crew Cab dually, 6.2, Banks, Th400, 4.10, Gear Vendors, 235-85R16
83 C20 Suburban, Sierra Classic, 6.2, 700R4, 4.10, custom paint, 285-50R20
95 Yukon, 6.5, 4L80E, 3.42, 265-50R20
73 GMC Astro 95, 8V71, 10 speed Roadranger, 110" WB, 6 each 11R24.5