When I pulled the engine, EVERYTHING looked OM, did not see anywhere that showed any type of mods to install another engine, the air cleaner duct (rotated it to get engine down, back, and out) aligned with the air cleaner that is mounted under the drivers seat. The 270 was around when the k18 was built, the civi version may have the 248, but based on what I laid hands on, I Think the ORIGINAL engine was/is the 270, because of what I saw AND the truck was made to pull the K19 (com trailer) and being the 248 would have been more then a bit UNDER POWER, the K18 got the 270 at factory build, so I TRULEY BELIEVE that the engine I pulled IS the ORIGINAL ENGINE..